Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
  • C07D277/60—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings condensed with carbocyclic rings or ring systems
  • C07D277/62—Benzothiazoles
  • C07D277/64—Benzothiazoles with only hydrocarbon or substituted hydrocarbon radicals attached in position 2
  • C07D277/66—Benzothiazoles with only hydrocarbon or substituted hydrocarbon radicals attached in position 2 with aromatic rings or ring systems directly attached in position 2
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
  • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
  • C12Q1/34—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase
  • C12Q1/37—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving hydrolase involving peptidase or proteinase
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
  • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
  • C12Q1/66—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving luciferase

Definitions

• Proteases constitute a large and important group of enzymes involved in diverse physiological processes such as blood coagulation, inflammation, reproduction, fibrinolysis, and the immune response. Numerous disease states are caused by, and can be characterized by, the alterations in the activity of specific proteases and their inhibitors. The ability to measure these proteases in research or clinically is significant to the investigation, treatment and management of disease states.
• caspases 3 and 7 are members of the cysteine aspartyl-specific protease (also known as the aspartate specific- cysteine protease, "ASCP") family and play key effector roles in apoptosis in mammalian cells (Thornberry et al., 1992; Nicholson et al., 1995; Tewari et al., 1995; and Fernandes-Alnemri et al., 1996).
• Proteases are not easy to assay with their naturally occurring substrates.
• many currently available synthetic substrates are expensive, insensitive, and nonselective.
• the use of high concentrations of the target protease, with either the naturally occurring substrate or a synthetic substrate may be required for the assay, which may result in the self destruction of the protease.
• modified luciferins have provided alternatives to fluorescent indicators (U.S. Patent Nos. 5,035,999 and 5,098,828).
• Methods for using modified luciferins with a recognition site for a hydrolase as a pro-substrate were first described by Miska and Geiger (1989). These heterogenous assays were conducted by incubating the modified luciferin with a hydrolase for a specified period of time, then transferring an aliquot of the mixture to a solution containing luciferase. Masuda-Nishimura et al.
• the invention provides a sensitive luminescent method to detect a protease, e.g., a caspase, trypsin or tryptase.
• a luminescent assay method to detect one or more caspases. The method comprises contacting a sample suspected of having one or more caspases with a mixture comprising beetle luciferase and an amino-modified beetle aminoluciferin or a carboxy-terminal protected derivative thereof, wherein the amino group of aminoluciferin or the derivative thereof is modified so as to covalently link a substrate for the caspase via a peptide bond to aminoluciferin or the carboxy-terminal protected derivative thereof.
• the substrate is cleaved at the peptide bond that links the substrate to aminoluciferin, yielding aminoluciferin, a substrate for the luciferase, in the mixture.
• Luminescence is then detected.
• the method further comprises correlating luminescence with protease concentration or activity, i.e., increased luminescence correlates with increased protease concentration or activity.
• the luminescent assay is more sensitive than a corresponding assay with a conjugate comprising a fluorophore covalently linked via an amide bond to at least one substrate molecule or a functional equivalent thereof.
• a conjugate comprising a fluorophore may be covalently linked to one or more molecules of the substrate.
• the luminescent assay is more sensitive than a corresponding assay which employs the fluorophore rhodamine-110, which can be modified via an amide bond to link two protease substrates to the fluorophore.
• a "functional equivalent" of a reference substrate is a substrate having one or more amino acid substitutions relative to the sequence of the reference substrate, which functionally equivalent substrate is recognized and cleaved by the same protease at a substantially similar efficiency as the reference substrate.
• Figure 13 shows exemplary functionally equivalent substrates for various caspases.
• the increased assay sensitivity with methods employing the luminescent substrates of the invention is at least 2 times, more preferably 3, 4, 5, 6, 7, 8, 9, or 10, or even greater, for instance, at least 15, 20, 25, 30, 40, 50, 100, 200, 500, or 1000 times or more, greater than that of an assay employing a conjugate comprising a fluorophore covalently linked to at least one substrate molecule or a functional equivalent thereof.
• the methods of the invention may detect less than 5 ⁇ U, or less, e.g., less than 1 ⁇ U, 0.5 ⁇ U or 0.2 ⁇ U of caspase in a sample.
• the limit of detection means 3 standard deviations above background noise ("noise" is 1 standard deviation of background and background is a control without caspase).
• the methods of the invention may be employed with a sample comprising purified or partially-purified preparations of enzyme, as well as a sample comprising a cell lysate or intact cells.
• a sample comprising purified or partially-purified preparations of enzyme
• a sample comprising a cell lysate or intact cells.
• accurate background levels of activity e.g., in resting cells such as those in the absence of inducer or toxin, can be readily and accurately established.
• the invention also provides a luminescent assay method to detect a protease that specifically cleaves a substrate comprising aspartate.
• the method comprises contacting a sample suspected of having one or more aspartate- specific proteases with a mixture comprising luciferase and an amino-modified aminoluciferin or a carboxy-terminal protected derivative thereof, wherein the amino group of aminoluciferin or the derivative thereof is modified so as to covalently link the substrate via a peptide bond to aminoluciferin or a carboxy- terminal protected derivative thereof.
• the substrate is cleaved at the peptide bond that links the substrate comprising aspartate to aminoluciferin, yielding aminoluciferin, a substrate for the luciferase in the mixture. Then luminescence is detected in the sample.
• the luminescent assay is more sensitive than a corresponding assay with a conjugate comprising a fluorophore covalently linked to one or more molecules of the substrate or a functional equivalent thereof.
• Preferred proteases that specifically cleave a substrate comprising aspartate include but are not limited to caspases, e.g., any one of caspases 1-14.
• Prefeoed substrates comprise Xj-X 2 -X -D, wherein Xi is Y, D, L, V, I, A, W, or P; X 2 is V or E; and X is any amino acid, for instance, a substrate comprising DEVD, WEHD, VDVAD, LEHD, VEID, VEVD, VEHD, IETD, AEVD, LEXD, VEXD, IEHD, or PEHD.
• the invention also provides a luminescent assay method to detect trypsin or tryptase.
• the method comprises contacting a sample suspected of having trypsin or tryptase with a mixture comprising luciferase and an amino-modified aminoluciferase or a carboxy-terminal protected derivative thereof, wherein the amino group of aminoluciferin or the derivative thereof is modified so as to covalently link a substrate for trypsin or trytase via a peptide bond to aminoluciferin or a carboxy-terminal protected derivative thereof. Luminescence is then detected.
• the luminescent assay is more sensitive than a corresponding assay with a conjugate comprising a fluorophore covalently linked to at least one substrate molecule or a functional equivalent thereof.
• a conjugate comprising a fluorophore covalently linked to at least one substrate molecule or a functional equivalent thereof.
• arginine and lysine are functionally equivalent substrates as trypsin cleaves the peptide bond after those residues with substantially similar efficiencies.
• the increased assay sensitivity with methods employing the luminescent substrates of the invention for trypsin or tryptase is at least 2 times, more preferably 3, 4, 5, 6, 7, 8, 9, or 10, or even greater, for instance, at least 15, 20, 25, 30, 40, 50 or 100 times or more, greater than that of an assay employing a conjugate comprising a fluorophore covalently linked to at least one substrate molecule or a functional equivalent thereof.
• a substrate for trypsin it was found that the limit of detection for a lysyl-amino luciferin substrate was 3.0 pg while that for the arginine 2 -rhodamine-l 10-based substrate was 12 to 30 pg.
• a trypsin assay which employs an amino-modified aminoluciferin substrate is at least 4 times more sensitive than a corresponding assay with a conjugate comprising rhodamine-110 covalently linked to two functionally equivalent trypsin substrates. Further provided is a luminescent assay method to detect a protease that specifically cleaves a substrate comprising arginine or lysine.
• the method comprises contacting a sample suspected of having one or more proteases specific for a substrate comprising arginine or lysine with a mixture comprising luciferase and an amino-modified aminoluciferase or a carboxy-terminal protected derivative thereof covalently linked via a peptide bond to a substrate comprising arginine or lysine.
• Luminescence in the sample is then detected.
• the assay is more sensitive than a corresponding assay with a conjugate comprising a fluorophore covalently linked to the substrate or a functional equivalent of the substrate.
• the methods of the invention may be of diagnostic use, or to monitor a mammal subjected to therapy, e.g., anti- inflammatory therapy.
• a compound comprising aminoluciferin or a carboxy- terminal protected derivative thereof covalently linked via a peptide bond to a protease recognition site such as a caspase recognition site, a trypsin recognition site, or a tryptase recognition site.
• kits useful in the methods of the invention are also envisioned.
• Such kits may comprise the amino-modified aminoluciferins or carboxy-terminal protected derivatives of the invention, and instructions for their use, optionally a luciferase, for instance a thermostable luciferase and also optionally a buffer for a luminescence reaction which may include a lysing agent.
• Figure 1 depicts relative light units (RLU) for luciferin or aminoluciferin as a substrate for a thermostable firefly luciferase in a luminescent reaction.
• Aminoluciferin produces about 60% of the light output as luciferin under saturating conditions.
• the K m shifts from about 0.6 ⁇ M for luciferin to 2 ⁇ M for aminoluciferin.
• Figure 2 illustrates the elimination of background signal from free aminoluciferin in a homogeneous assay format.
• Free aminoluciferin can produce high background signal even in the absence of trypsin. This background signal decreases as the free aminoluciferin is consumed by luciferase.
• the signal to noise ratio is dramatically increased.
• the presence of the protease did not interfere with the luciferase reaction.
• Figure 3A shows RLU from a trypsin titration with N-Lys-aminoluciferin over time. Substrate was combined with luciferase, ATP, and Mg+ in buffer and incubated overnight to eliminate free aminoluciferin. The substrate mixture was then added to the trypsin titrations.
• Figure 3B shows RLU (log) from a trypsin titration with N-Lys- aminoluciferin over an extended period of time.
• Figure 4 depicts relative fluorescent units (RFU) from a trypsin titration with Z-Arg-Rho 110.
• Figure 5 shows RLU from a caspase titration with Z-DEVD- aminoluciferin over time. Luciferase, ATP, and Mg+ in buffer were added to the substrate.
• Figure 6 shows RFU from a caspase titration with Z-DEVD-Rhol 10.
• the fluorescent Z-DEVD-Rhol 10 substrate was provided in the Apo-ONETM Homogeneous Caspase 3/7 Assay kit (Promega). The same buffer was used for the DEVD-Rhol 10 substrate as for the DEVD-aminoluciferin substrate (see Figure 5).
• Figure 7 shows RFU (background subtracted) or RFU (log) for caspase and Z-DEVD-Rhol 10.
• Figure 8 shows RLU (background subtracted) or RLU (log) for caspase and Z-DEVD-aminoluciferin.
• Figure 9 is a comparison of RLU and RFU for trypsin with N-Lys- aminoluciferin or Z-Arg-Rho 110 as a substrate. Trypsin titrations were set up as described above. The luminescent assay was more sensitive than a comparable fluorescent assay, e.g., the Lys-amino luciferin substrate has a sensitivity 3-10 fold greater than the Arg-Rhol 10 depending on the time of the reading.
• Figure 10 is a comparison of RLU and RFU for caspase and Z-DEVD- aminoluciferin, Z-DEVD-AMC or Z-DEVD-Rhol 10 as a substrate.
• the Z- DEVD-Rho 110 substrate and buffer used were the Apo-ONETM (Promega) substrate and buffer. The same buffer was used for the DEVD-AMC substrate.
• the DEVD-aminoluciferin substrate had a sensitivity 50-300 fold greater than the Arg-Rhol 10 depending on the time of the readings.
• Figure 11 shows RLU or RFU obtained with Jurkat cells (induced or uninduced) and the caspase substrate Z-DEVD-aminoluciferin or Z-DEVD- Rhol 10.
• the Apo-ONETM buffer and Z-DEVD-Rhol 10 substrate were used for the fluorescent caspase assay.
• the same buffer was used for the DEVD- aminoluciferin substrate with the addition of luciferase, ATP, and MgSO 4 .
• the DEVD-aminoluciferin substrate has a sensitivity 10-fold greater than the Arg- Rhol 10 at the 1 hour time point. At 4 hours, this decreased to about 2-fold.
• Figure 12 shows relative RLU or RFU results obtained using CHAPS or Apo-ONETM buffer.
• Figure 13 illustrates recognition sites for various caspases (Thornberry et al, 1997; Garcia-Calvo et al., 1999).
• Rapid and sensitive assays of proteolytic activity are important for general characterization of proteases and high-throughput screening for protease inhibitors.
• the inherent background of fluorescence particularly in cell-based systems, can limit assay sensitivity.
• lengthy incubations are often required for accumulating the fluorescent assay product.
• Luminescent assays can often provide greater sensitivity in less time.
• the present invention provides an improved, sensitive method for monitoring protease activity in purified preparations comprising the protease, in cell lysates or cells, either prokaryotic or eukaryotic cells.
• Preferred eukaryotic cells include mammalian cells, for example, human, feline, bovine, canine, caprine, ovine, swine, equine, non-human primate, e.g., simian, avian, plant or insect cells.
• the cells may be cells that have not been genetically modified via recombinant techniques (nonrecombinant cells), or recombinant cells, the genome of which is augmented with a recombinant DNA.
• the DNA may encode a protease to be detected by the methods of the invention, a molecule which alters the level or activity of the protease in the cell, and/or a molecule unrelated to the protease or molecules that alter the level or activity of the protease.
• the protease is detected using an amino-modified aminoluciferin or a carboxy-terminal protected derivative thereof, which modification comprises a substrate for the protease.
• the substrate which comprises one or more amino acid residues which include the recognition site for the protease, is covalently linked to the amino group of aminoluciferin or the carboxy-terminal modified derivative via a peptide bond.
• the N-terminus of the substrate is modified to prevent degradation by aminopeptidases, e.g., using an amino- terminal protecting group.
• a mixture comprising a substrate and luciferase will generate minimal light as minimal aminoluciferin is present (a small amount of light may be generated due to spontaneous hydrolysis of the peptide bond).
• the peptide bond linking the substrate and aminoluciferin (the bond immediately adjacent to the 6' position on the luciferin core molecule) can be cleaved by the protease to yield aminoluciferin, a substrate for luciferase.
• luciferase for instance, a native, a recombinant or a mutant luciferase, light is generated, which is proportional to the amount or activity of the protease.
• any beetle luciferase preferably a thermostable luciferase, may be employed in the methods of the invention.
• the aminoluciferin-based substrates of the invention are relatively inexpensive to synthesize and can be purified to high levels. Moreover, because they are extremely sensitive substrates, only very small amounts of a biological sample (e.g., cells, and physiological fluids, blood, urine, etc., which comprise cells) are required to perform the assay. Further, because the aminoluciferin- based substrates are extremely selective, little or no purification of the biological sample is required.
• Rhodamine-110 is likely one of the most sensitive indicators known.
• the sensitivity described herein for a caspase is superior to Apo-ONETM (Promega, Madison, WI).
• Apo-ONETM is a fluorescent based assay, which uses the fluorphore Rhodamine-110 conjugated to 2 recognition sequences for caspase 3/7.
• the methods of the invention are employed as a homogeneous assay for a protease, such as a caspase, tryptase or trypsin, i.e., the modified aminoluciferin, luciferase and additional components are mixed prior to adding the mixture to the sample. Results may be read without additional transfer of reagents.
• a protease such as a caspase, tryptase or trypsin, i.e., the modified aminoluciferin, luciferase and additional components are mixed prior to adding the mixture to the sample. Results may be read without additional transfer of reagents.
• a specific compound of the invention is a compound of formula (I):
• R is a peptide that is a substrate for caspase, trypsin and tryptase, which is linked to the remainder of the compound of formula (I) through its C-terminus forming a peptide (amide) bond; and R' is H or a suitable carboxy protecting group (e.g. a (C ⁇ -C 6 )alkyl, phenyl or benzyl ester), or a suitable salt thereof.
• R is a peptide that is a substrate for caspase, trypsin and tryptase, which is linked to the remainder of the compound of formula (I) through its C-terminus forming a peptide (amide) bond
• R' is H or a suitable carboxy protecting group (e.g. a (C ⁇ -C 6 )alkyl, phenyl or benzyl ester), or a suitable salt thereof.
• Another specific compound of the invention is a compound of formula
• R is a peptide that is linked to the remainder of the compound of formula (I) through an aspartate, lysine, or arginine group at the C-terminus of the peptide forming a peptide (amide) bond; and R' is H or a suitable carboxy protecting group (e.g. a (C ⁇ -C 6 )alkyl, phenyl or benzyl ester), or a suitable salt thereof.
• a suitable carboxy protecting group e.g. a (C ⁇ -C 6 )alkyl, phenyl or benzyl ester
• salts of the amino-modified aminoluciferin compounds or the carboxy-terminal protected derivatives thereof can also be used in the methods described herein, and also form part of the invention. Methods for preparing suitable salts are known in the art.
• Compounds of the invention can be prepared using procedures that are generally known, or they can be prepared using the procedures described herein.
• compounds of the invention can be prepared using standard solution phase chemistry. Accordingly, a peptide can be coupled to an amino-cyanobenzothiazole, followed by reaction with D-cysteine to provide a compound of the invention.
• amino-cyanobenzothiazole can first be reacted with D-cysteine to provide an intermediate amino compound, which can subsequently be conjugated to a peptide to provide a compound of the invention.
• an aminoluciferin labeling reagent in the form of an N-protected amino acid that is attached to a peptide synthesis resin via the carboxylic acid function can be prepared using standard coupling reagents (e.g., ED AC, DCC, or HOBt).
• the N-protective group is preferably Fmoc or t-Boc, but can be any group that can be removed without deleterious effect on the chemical bond connecting the label to the resin.
• the labeled peptide is cleaved from the resin using standard cleavage reagents to provide the carboxylic acid.
• the invention provides aminoluciferin coupled via the free carboxyl group to a solid support for the purposes of peptide synthesis.
• Such a carboxy-terminal protected aminoluciferin is convenient for the synthesis of a conjugate comprising a peptide of interest conjugated to the amino group of aminoluciferin.
• the amino group is protected with an Fmoc or a t- Boc group.
• the invention also provides a method for preparing a compound of the invention comprising forming an amide bond between the amino group of a solid support bound aminoluciferin and a first amino acid or a first peptide; and optionally attaching one or more additional amino acids or peptides through peptide bonds to provide the compound.
• the solid support bound aminoluciferin can optionally be prepared by attaching an N-protected aminoluciferin to a solid support through the carboxy group; and deprotecting the aminoluciferin.
• the support bound compound can then be removed to provide the corresponding free carboxylic acid, which can optionally be protected to provide a carboxyterminal protected derivative.
• a carboxy-protected derivative of the invention can be prepared from the corresponding carboxylic acid using standard techniques. Accordingly, the invention provides a method to prepare a carboxy-terminal protected derivative of aminoluciferin, comprising protecting the corresponding acid with a suitable carboxy-protecting group.
• Suitable amino protecting groups e.g. Fmoc or t-Boc
• suitable carboxy protecting groups e.g. (C]-C 6 )alkyl, phenyl or benzyl esters or amides
• Example 1 To compare the limit of detection for a luminescence-based and a fluorescence-based assay for trypsin, two substrates, Lys-aminoluciferin (Cbz- modified lysinyl-amino luciferin) and Arg-Rho-110 (Molecular Probes, Catalog no. R6501), were used. Substrate was resuspended in 100 mM Hepes, pH 7.9, at a concentration of 10 mM and stored at -20°C.
• Lys-aminoluciferin Cbz- modified lysinyl-amino luciferin
• Arg-Rho-110 Molecular Probes, Catalog no. R6501
• the thawed Lys-aminoluciferin substrate, thermostable luciferase (5.2 mg/ml stock), and ATP (0.1 M stock) were diluted in buffer (50 mM HEPES, pH 7.9, 10 mM MgSO 4 , 1 mM EDTA, pH 8.2 and 0.1% prionex) to make a stock that was lOx the final concentration.
• the lOx stock was 200 ⁇ M Lys-aminoluciferin, 200 ⁇ g/ml luciferase, and 2.0 mM ATP. This lOx stock was incubated for at least 90 minutes to eliminate any free aminoluciferin.
• Trypsin was prepared for titration as follows: 1 ⁇ g/ ⁇ l stock solution was diluted to 10 ng/50 ⁇ l in the same buffer as above (50 mM HEPES, pH 7.9, 10 mM MgSO 4 , 1 mM EDTA, pH 8.2 and 0.1% prionex). This 10 ng/ ⁇ l trypsin solution was serially diluted 5 fold to 2 ng, 0.4 ng, 0.08 ng, 0.016 ng, 3.2 pg, 0.64 pg, 0.128 pg, 0.0256 pg and 0.005 pg. The trypsin dilutions were added to two 96-well plates in replicates of 8 at 50 ⁇ l per well. Pipette tips were changed for each row to avoid enzyme carryover. Two columns (16 wells) contained buffer only without trypsin.
• the second plate of trypsin dilutions was used to test the Arg-Rho-110 substrate ( Figure 4).
• the Arg-Rho-110 substrate was tested at final concentrations of 10 ⁇ M and 2.5 ⁇ M.
• 2x stocks of 20 ⁇ M and 5 ⁇ M were prepared by diluting the substrate in 50 mM HEPES, pH 7.9, 10 mM MgSO 4 , 1 mM EDTA, pH 8.2 and 0.1% prionex.
• To each well of the plate containing 50 ⁇ l of the trypsin titration was added 50 ⁇ l of either the 20 ⁇ M or 5 ⁇ M 2x stocks of Arg-Rho-110 substrate.
• the 20 ⁇ M stock was added to the first four rows (final concentration of 10 ⁇ M in rows A-D) and the 5 ⁇ M stock was added to the second four rows (final concentration of 2.5 ⁇ M in rows E-H).
• the substrate mix was also added to 12 of the 16 wells containing buffer only without trypsin. The remaining 4 wells were left with buffer only (no substrate mix).
• the Arg-Rho- 110 plate was incubated at room temperature in the dark for 4.5 hours and read on a fluorimeter.
• the signal to noise was calculated as signal-background (no trypsin)/S.D. of background.
• the limit of detection was determined as 3 S.D. above background noise.
• a homogeneous format was used for a trypsin assay.
• the luminescent assay reached a maximum sensitivity in 30 minutes or less and was very stable for extended time periods.
• Example 2 To determine the effect of an overnight pre-incubation of substrate with luciferase, ATP and buffer prior to adding trypsin, a substrate/luciferase/ATP mix was incubated overnight in the dark, at room temperature.
• Lys- aminoluciferin substrate the thawed Lys-aminoluciferin substrate (10 mM stock), thermostable luciferase (5.2 mg/ml stock), and ATP (0.1 M stock) were diluted in buffer (50 mM HEPES, pH 7.9, 10 mM MgSO 4 , 1 mM EDTA, pH 8.2 and 0.1%) prionex) to make a stock that was lOx the final concentration.
• the lOx stock was 200 ⁇ M Lys-aminoluciferin, 200 ⁇ g/ml luciferase, and 2.0 mM ATP. After overnight incubation, the lOx stock was diluted in buffer to make a 2x stock (40 ⁇ M of substrate, 400 ⁇ M of ATP and 40 ⁇ g/ml of luciferase).
• the Arg-Rho-110 substrate was also prepared to a 2x working stock concentration of 40 ⁇ M from a 5 mM stock.
• Trypsin dilutions were prepared from a 1 ⁇ g/ ⁇ l stock and diluted to the same concentrations as in Example 1, and two different plates were set up with 4 wells for each concentration of trypsin, 50 ⁇ l per well. Two columns had buffer only without trypsin as a control. Then, 50 ⁇ l of the 2x Lys-aminoluciferin substrate mix was added to each well of one plate, and the results were read at several time points on a luminometer. To the second plate, 50 ⁇ l of the 2x Arg- Rho-110 stock was added to each well for a final concentration of 20 ⁇ M, as in Example 1. The luminescence-based assay was able to detect as little as 3.0 pg of trypsin, while the fluorescence-based assay had a limit of detection of about 12- 30 pg (4-10 times less enzyme).
• Example 3 To conduct a direct comparison between luminescent and fluorescent substrates for caspase 3, DEVD-Rho-110 and DEVD-aminoluciferin were employed.
• the DEVD-aminoluciferin substrate/luciferase/ATP mixture was prepared first and preincubated prior to the enzyme assay to eliminate free aminoluciferin.
• Apo-ONETM buffer Promega
• 10 ⁇ l of DEVD-luciferin (10 mM stock) 10 ⁇ l of ATP (0.1 M stock), 50 ⁇ l of MgSO 4 (1 M stock), 50 ⁇ l of prionex (10% stock), and 48 ⁇ l of luciferase (5.2 mg/ml stock).
• the volume was brought up to 2.5 ml with nanopure, autoclaved water to make a 2x stock of 40 ⁇ M DEVD-luciferin, 400 ⁇ M ATP, 0.2% prionex, and 100 ⁇ g/ml luciferase. This stock was incubated overnight at room temperature.
• Caspase (Upstate Biotech, Cat. No. 14-264; approximately 10 mU/ng protein with > 75% in active conformation) was diluted 550 fold in a 50/50 mixture of Apo-ONETM buffer/RPMI- 1640 culture media, from 1 U/ ⁇ l to
• the final caspase concentrations were 10 mU, 1 mU, 0.1 mU, 0.01 mU, 0.001 mU, 0.1 ⁇ U, 0.01 ⁇ U, 0.001 ⁇ U, 0.1 nU, and 0.01 nU/well.
• the last two columns were buffer/media only without caspase.
• DEVD- aminoluciferin was 10-100 times more sensitive than DEVD-Rho-110 ( Figure 10).
• the fluorescent ratio assay required several hours for maximum sensitivity and was always changing over time. Moreover, the fluorescent assay lost linearity at low caspase concentrations.
• the luminescent assay is a rate assay that is not dependent on the accumulation of cleaved substrate. Therefore, steady-state (protease cleavage versus luciferase consumption of aminoluciferin) is reached rapidly and this steady-state is stable for several hours. Moreover, linearity is also maintained for several hours. The luminescent assay reached a maximum sensitivity in 30 minutes or less and was very stable for extended time periods. The luminescent assay was linear over 3-4 logs at low caspase concentration (Figure 8).
• Example 4 The DEVD-aminoluciferin caspase substrate and the DEVD-Rho-110 caspase substrate were used to measure caspase activity in Jurkat cells induced to undergo apoptosis with anti-FAS antibody. DEVD-luciferin and luciferase were prepared for pre-incubation prior to use in the assay. Substrate, ATP,
• MgSO , prionex and luciferase were diluted from the same stock as in Example 3 to the same 2x concentration, except that the components were diluted in autoclaved water rather than Apo-ONETM. This mixture was incubated overnight in the dark (covered in foil). The next day, Jurkat cells, grown in RPMI- 1640 media with 10% Fetal
• Bovine Serum (FBS) to a density of 5 x 10 5 cells/ml, were treated with anti-FAS antibody.
• To one vial of 8 ml of media was added 1.6 ⁇ l of antibody (1 :5000 dilution); a second vial contained 8 ml of media and no antibody.
• Cells were incubated for 4 hours at 37°C, in 5% CO 2. Cells were then centrifuged and resuspended in 12.5 ml of RPMI-1640 to a density of 3.2 x 10 5 cells/ml, then diluted 1 :1 with Apo-ONETM buffer for 1.6 x 10 5 cells/ml, or 8,000 per 50 ⁇ l.
• Two 96-well plates were prepared such that on each, the first column was left empty, and 50 ⁇ l of RPMI- 1640: Apo-ONETM solution was placed in each of the remaining wells.
• 100 ⁇ l of the "induced" cell solution (8,000 cells) was added and the cells then serially diluted from 8,000 cells/well, to 4,000 cells/well and so on, down to 7.8 cells/well.
• the twelfth column was left without cells and with only 50 ⁇ l of RPMI-1640:Apo- ONETM solution.
• the next four rows on each plate were likewise treated with
• One of the two plates was treated with 50 ⁇ l of either DEVD- aminoluciferin/luciferase mix or with DEVD-Rho-110/ Apo-ONETM (Promega G778B and G777B). Each plate was mixed on a plate shaker for 30 seconds then incubated at room temperature and read on either a Dynex luminometer or
• Fluoroskan plate reader at 1 hour, 2 hours, 4 hours and one day later.
• the aminoluciferin substrate assay showed that the assay detects caspase positive cells in a well having 15 cells in as little as 1 hour, and that the assay remains linear at the 4 hour time point (Figure 11). On the other hand, the aminoluciferin substrate assay showed that the assay detects caspase positive cells in a well having 15 cells in as little as 1 hour, and that the assay remains linear at the 4 hour time point (Figure 11). On the other hand, the
• DEVD-Rho-110 substrate assay had a limit of detection of 150 cells/well at 1 hour, and about 30 cells at 4 hours.
• Example 5 To evaluate different assay component formulations for caspase-3 activity and to compare sensitivities of DEVD-aminoluciferin to DEVD-Rho- 110 in those formulations, two stock solutions were prepared. As above, the DEVD-aminoluciferin/luciferase mixture is prepared and allowed to incubate overnight. One stock solution included a 1% solution of CHAPS buffer (Sigma, Catalog No. C-5070) and the other a 1% solution of Thesit (Pragmatics, Inc., Catalog No. S-22#9).
• the buffer formulations were as follows: 100 ⁇ l of HEPES (1 M stock, 50 mM final concentration), 10 ⁇ l of CaCl 2 (1 M stock, 5 mM final concentration), 30 ⁇ l of MgSO 4 (1 M stock, 15 mM final concentration), 8 ⁇ l of ATP (0.1 M stock, 400 ⁇ M final concentration), 8 ⁇ l of DEVD-aminoluciferin (10 mM stock, 40 ⁇ M final concentration), 38.4 ⁇ l of luciferase (5.2 mg/ml stock, 100 ⁇ g/ml final concentration) and 20 ⁇ l of prionex (10% stock, 0.1%) final concentration) were combined in each of 2 tubes.
• the caspase buffer was as follows: HEPES, CHAPS or Thesit, CaCl 2 , MgSO , DTT and prionex, all in the same final concentrations as described above.
• the caspase was serially diluted by factors of 10, from 1 mU through 1 x 10 "8 mU to a final volume of 440 ⁇ l of each dilution. 50 ⁇ l of each of these dilute caspase solutions were added to each of 3 wells on each of two 96 well plates. Three columns of wells were left blank.
• Analytical Reverse-phase HPLC was performed using a Synergi 4 ⁇ Max- RP column, 4.6 mm x 50 mm, on Beckman System Gold 126 pump systems equipped with a Model 168 diode-array detector and Model 507 autosampler.
• the solvents were: A — 10 mM sodium phosphate buffer (pH 7.0) and B— methanol. All analytical reverse-phase chromatograms were monitored at 254 nm and 315 nm.
• Nmr spectra were obtained on a Varian 300 Mhz spectrometer.
• the reaction flask was fitted with a condenser and the mixture was then heated at 35- 38 °C using a water bath for 1.5 h, during which time the mixture clarified somewhat.
• the reaction was cooled and concentrated by rotoevaporation to a residue, which was suspended in ethyl acetate (50 mL) and washed twice with 10 mL of 10%) aqueous citric acid solution.
• the organic layer was then washed twice with 10 mL of water, and the water layer was back-extracted with ethyl acetate.
• the organic layers were combined, dried over anhydrous sodium sulfate, concentrated by rotoevaporation, and coevaporated twice with dichloromethane to afford 500 mg of crude off-white foam.
• This crude material was purified by flash chromatography on silica gel (25 g) using a step-wise solvent gradient of 5%-20%> methanol in dichloromethane to provide 190 mg (56%) of Z-Asp(OtBu)-Glu(OtBu)-Val-Asp(OtBu)-OH as an off-white foam.
• the resulting solution was added in portions via pasteur pipet to the flask containing the D-cysteine solution, with periodic addition of 6N hydrochloric acid as needed to maintain a pH less than 7.0.
• a portion of the reaction mixture (0.24 mL, containing approximately 0.047 mmoles of D-cysteine) was measured (via pipet) and transferred to a separate 5 mL reaction vial.
• N-Fmoc-aminoluciferin 2-[6'-(9-fluorenylmethoxycarbonyl)amino-2'-benzothiazolyl]- ⁇ 2 - thiazoline-4-carboxylic acid (N-Fmoc-aminoluciferin).
• N-trifluoroacetyl-amino luciferin 660 mg, 1.76 mmol
• methanolic ammonia 30 mL of a 7 M solution, 210 mmol
• the reaction mixture was concentrated by rotoevaporation and then coevaporated with dichloromethane to give 626 mg of a crude brown solid residue that was used in the next step without purification.
• a portion of the crude brown solid residue (391 mg) was dissolved in methanol (40 mL) and water (2 mL) in a 100 mL round-bottomed flask.
• Fmoc-Cl 435 mg, 1.68 mmol
• the product was purified by flash chromatography on 3 successive silica gel columns using 100 g for the first 2 columns and 150 g for the third.
• the eluting solvent for the first column was 98:2 dichloromethane- methanol.
• the eluting solvent for the second column was 93:7 dichloromethane- methanol.
• the eluting solvent for the third column was 97:3 dichloromefhane- methanol.
• Fractions containing product were combined and concentrated to provide 280 mg of waxy product that was 95% pure and 320 mg of product that was 89%> pure.
• the 280 mg of waxy material was re-purified on 25 g of silica gel using 4:1 dichloromethane-methanol to give 108 mg of dry pale yellow solid.
• the intermediate compound N-trifluoroacetyl-aminoluciferin was prepared as follows.
• the resulting solution was added in portions via pasteur pipet to the flask containing the D, L- cysteine solution, with periodic addition of 6N hydrochloric acid as needed to maintain a pH less than 7.5.
• a portion of the reaction mixture (10.1 mL, containing approximately 2.04 mmoles of D, L-cysteine) was measured (via graduated cylinder) and transferred to a separate 50 mL erlenmeyer flask.
• This mixture was diluted with 15 mL of degassed methanol and the resulting solution was transferred to a 100 mL round-bottomed flask containing a solution of 2- cyano-6-trifluoroacetylaminobenzothiazole (White et al., 1966) (552 mg, 2.04 mmol) in degassed methanol (17 mL).
• the reaction mixture was magnetically stirred at room temperature and the reaction flask was covered with aluminum foil. After stirring for 1 h, TLC and HPLC analysis indicated only traces of starting material remaining.
• the reaction mixture was diluted with water (79 mL) and the pH was found to be -8.0.
• the reaction mixture was transferred to a separatory funnel (250 mL) and extracted with ethyl acetate (79 mL) to remove neutral organic compounds.
• the aqueous phase was acidified to pH 2 by addition of 6N hydrochloric acid, resulting in a sticky off-white precipitate that was stored overnight at 5 °C.
• the suspension was transferred to 50-mL centrifuge tubes and centrifuged for about 3 min. The supernatant was decanted and the pellet was washed with cold water and centrifuged three times. The pellet was suspended in methanol and transferred to a 250 mL round-bottomed flask.

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=27734277

Family Applications (1)

Country Status (6)

Cited By (19)

Families Citing this family (19)

Citations (1)

Family Cites Families (33)

• 2003
  • 2003-01-31 US US10/356,665 patent/US7148030B2/en active Active
  • 2003-01-31 EP EP10075526.3A patent/EP2388254B1/en not_active Expired - Lifetime
  • 2003-01-31 WO PCT/US2003/002936 patent/WO2003066611A1/en active Application Filing
  • 2003-01-31 JP JP2003565985A patent/JP4451663B2/ja not_active Expired - Lifetime
  • 2003-01-31 CA CA002474695A patent/CA2474695A1/en not_active Abandoned
  • 2003-01-31 EP EP03737580A patent/EP1472238B1/en not_active Expired - Lifetime
  • 2003-01-31 AU AU2003216139A patent/AU2003216139B2/en not_active Ceased
• 2006
  • 2006-02-02 US US11/346,043 patent/US7384758B2/en not_active Expired - Lifetime
  • 2006-02-03 US US11/347,054 patent/US7666987B2/en not_active Expired - Lifetime
• 2010
  • 2010-02-16 US US12/706,078 patent/US8071328B2/en not_active Expired - Fee Related

Patent Citations (1)

Non-Patent Citations (17)

Also Published As

Similar Documents

Legal Events