JPH07194395A - Reagent for measuring inorganic phosphorus - Google Patents

Abstract

PURPOSE:To obtain a reagent for measuring inorganic phosphorus useful for an automatic analyzer, etc., having stability for a long period of time, not requiring dissolution operation, comprising a first reagent containing xanthine oxidase, purine nucleoside phosphorylase, etc., and a second reagent containing inosine, etc. CONSTITUTION:This reagent for measuring inorganic phosphorus is obtained by blending a first reagent containing at least xanthine oxidase and purine nucleoside phosphorylase with a second reagent containing at least inosine and, further, peroxidase, 4-aminoantipyrine and N-ethyl-N-sulfopropyl-m-toluidine each in a liquid reagent, respectively. By using the reagent, inorganic phosphorus in the specimen is reacted with inosine in the presence of purine nucleoside phosphorylase, formed hypoxanthine is treated with hypoxanthine oxidase, formed H2O2 reacted with 4-aminoantipyrine and N-ethyl-N-sulfopropyl-m- toluidine and a formed quinoid coloring matter is measured to determine inorganic phosphorus.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a reagent for measuring inorganic phosphorus. More specifically, it relates to a liquefied reagent composition for long-term stable inorganic phosphorus measurement.

[0002]

2. Description of the Related Art Phosphorus of human body (inorganic phosphorus or organic phosphorus)
Forms bone, constitutes a high-energy phosphorylated compound, a nucleic acid, a phospholipid, and the like, and also contributes to retaining the buffering capacity of blood. Inorganic phosphorus is metabolically regulated by various hormones and vitamin D, and it is important to measure the concentration in blood or urine in order to know the dynamics of electrolyte metabolism together with calcium. Clinically, renal hyperfunction and bone metabolism are well reflected, and marked hyperphosphatemia is seen especially in chronic renal failure with decreased urinary excretion.

Various inorganic phosphorus measuring methods have been established and have their respective characteristics. For example, a method in which inorganic phosphorus in a sample is reacted with ammonium molybdate in an acidic solution, and the resulting ammonium phosphomolybdate is colorimetrically measured to obtain the amount of inorganic phosphorus, or ammonium phosphomolybdate is further reduced to give molybdenum. There was a method of obtaining an amount of inorganic phosphorus by making it blue and measuring this colorimetrically. However, these methods have various problems such as complexity of operation, low sensitivity, coloring and corrosion of equipment.

Therefore, in recent years, a measuring method consisting of the following steps is often used. That is, purine nucleoside phosphorylase (hereinafter abbreviated as PNP) and xanthine oxidase (hereinafter abbreviated as XOD) are caused to act on inorganic phosphorus in a sample in the presence of inosine to generate H ₂ O ₂ , and then this H 2 ₂ O ₂ peroxidase (hereinafter PO
In the presence of D), 4-aminoantipyrine (hereinafter abbreviated as 4AAP) as a coupler and N-ethyl-N-sulfopropyl-m-toluidine (hereinafter abbreviated as ESPT) as a hydrogen donor), N- Ethyl-N- (2-hydroxy-3-sulfopropyl) 3,5-dimethoxyaniline (abbreviated as DAOS hereinafter) or N- (2-hydroxy-3-sulfopropyl) 3,5-dimethoxyaniline (abbreviated as HDAOS hereinafter) ) And the like to form a quinoid pigment by an oxidative condensation reaction, and the pigment obtained is colorimetrically measured to determine the amount of inorganic phosphorus. This measurement method is widely used because it has excellent reproducibility and linearity, and there is no concern about coloring or corrosion of equipment.

[0005]

However, in the above-mentioned method for forming a quinoid pigment, an unstable enzyme such as PNP or XOD is used, and it is difficult to store it in a liquid state for a long time. Was supplied as. In addition, since the stability conditions of each component also differ, the stability of the reagents when they are made up greatly changes depending on the combination of each component, and in the case of a liquid reagent in particular, the ordinary combination maintains stability for a long period of time. Was difficult.

On the other hand, with the spread of automatic analyzers, the reagent composition of the inorganic phosphorus measuring method has been changed from the one-reagent system to the two-reagent system. A conventional combination of reagent compositions in a two-reagent system is such that the first reagent is composed of XOD, POD, ESPT and inosine and the second reagent is composed of PNP and 4AAP, or the first reagent is composed of XOD, POD and ESPT. The second reagent was composed of inosine, PNP and 4AAP, but the storage stability in liquid form was extremely poor. Further, in recent years, it has been required to improve the workability of the user by preparing a reagent from a liquid form at the time of supply, rather than preparing the reagent in a liquid form at the time of use.

As a result of intensive studies to solve such conventional problems, the present inventors have found a reagent composition having sufficient storage stability for a long period of time even when supplied in the form of a liquid reagent. Furthermore, as a result of investigating the stabilization of the enzyme in this reagent composition, we succeeded in finding a suitable stabilizer. The present invention is based on these findings.

[0008]

The present invention provides a reagent for measuring inorganic phosphorus containing purine nucleoside phosphorylase, xanthine oxidase, peroxidase, inosine, 4-aminoantipyrine and N-ethyl-N-sulfopropyl-m-toluidine. 2. A reagent for measuring inorganic phosphorus, comprising a first reagent containing at least xanthine oxidase and purine nucleoside phosphorylase, and a second reagent containing at least inosine, each being a liquid reagent.

The present invention will be described in detail below. The measurement method to which the reagent for measuring inorganic phosphorus according to the present invention can be applied is obtained by reacting inosine with inorganic phosphorus in a sample in the presence of purine nucleoside phosphorylase (PNP) to produce hypoxanthine. Xanthine oxidase (XOD) is allowed to act on hypoxanthine to generate hydrogen peroxide, and the resulting hydrogen peroxide is treated with 4-aminoantipyrine (4AA) in the presence of peroxidase (POD).
P = coupler) and N-ethyl-N-sulfopropyl-
It consists of reacting m-toluidine (ESPT = hydrogen donor) to form a quinoid dye and measuring the increased amount of the quinoid dye thus formed. This measuring method can be represented by a reaction formula as follows.

[0010]

The reagent for measuring inorganic phosphorus of the present invention used in the method for measuring inorganic phosphorus comprising the above-mentioned reaction steps comprises (1) a liquid first reagent containing at least XOD and PNP, and (2) a liquid first reagent containing at least inosine. It consists of two reagents. When inosine and PNP coexist, these react with each other during storage and have a great influence on the measurement of inorganic phosphorus (probably because a xanthine-like substance is produced). It is necessary to separate the two in order to avoid this effect.

Further, when the inorganic phosphorus is measured using these first reagent and second reagent, it is preferable to eliminate the endogenous xanthine in the sample in advance. For this reason,
It is preferable to add XOD to the first reagent that first comes into contact with the sample, and further add ESPT to the first reagent or further add catalase to the first reagent. In the latter case, ESPT is added to the second reagent. Further, ESPT and catalase may be added to the first reagent and POD may be added to the second reagent. That is, X
When the first reagent containing OD is brought into contact with the sample, the X
OD acts on endogenous xanthine to produce H ₂ O ₂ . If ESPT is further present in the first reagent, ESP
The self-condensation reaction by T erases H ₂ O ₂ . When catalase is present in the first reagent, H ₂ O ₂ is erased by the elimination reaction by catalase. When the second reagent containing inosine is brought into contact with the sample after eliminating the influence of the endogenous xanthine in this way, the inorganic phosphorus, which is the measurement target, is present in the presence of inosine as PNP and XOD.
Generates H ₂ O ₂ by the action, the H ₂ O ₂ is POD
The coupler and the hydrogen donor are subjected to oxidative condensation reaction in the presence of to form a quinoid dye. At this time, inosine and PNP
It is preferred to add PNP to the first reagent to avoid coexistence with.

Therefore, the first reagent is XOD, PNP and P.
OD is contained, the second reagent contains inosine and 4AAP, and ESPT is added to the first reagent (elimination by self-condensation reaction) in order to eliminate the endogenous xanthine in advance. It is preferable to have a reagent configuration in which catalase is added to the reagent and ESPT is added to the second reagent (elimination reaction by catalase). The H ₂ O and O ₂ that participate in the above reaction step are supplied from the sample.

The origin of XOD contained in the first reagent is not particularly limited, but a microorganism-derived XOD is preferably used. The addition amount can be appropriately selected in consideration of each specific measurement system, but is generally 1 to 100 U /
ml, preferably 5 to 50 U / ml. 1U
If it is less than / ml, sufficient enzyme activity cannot be obtained. 10
There is no problem in measurement even if it exceeds 0 U / ml, but it is not necessarily advantageous in view of the problem of contamination of impurities and cost, and it is not necessary to add an excessive amount more than necessary.

The origin of PNP is not particularly limited, and PNP derived from animal tissue, erythrocyte or yeast can be used. The addition amount can be appropriately selected in consideration of each specific measurement system, but is generally 0.1 to 10
U / ml, preferably 0.5 to 5 U / ml. If it is less than 0.1 U / ml, sufficient enzyme activity cannot be obtained. There is no problem in measurement even if it exceeds 10 U / ml, but it is not necessarily advantageous from the viewpoint of the problem of mixing impurities and the cost, and it is not necessary to add an excessive amount more than necessary.

The origin of POD is not particularly limited, and POD derived from animal tissue or horseradish can be used. The addition amount can be appropriately selected in consideration of the individual specific measurement system, but is generally 1 to 100 U / m.
1, preferably 5 to 50 U / ml. 1U /
If it is less than ml, sufficient enzyme activity cannot be obtained. 100
Even if it exceeds U / ml, there is no problem in measurement, but it is not necessarily advantageous in terms of the problem of contamination of impurities and the cost, and it is not necessary to add an excessive amount more than necessary.

The addition amount of inosine contained in the second reagent is also
Although it can be appropriately selected in consideration of the individual specific measurement system, it is generally 0.5 to 50 mM, preferably 1 to 10
It may be mM. If it is less than 0.5 mM, a sufficient enzymatic reaction does not occur. Although there is no problem in measurement even if it exceeds 50 mM, it is not necessarily advantageous in terms of problems of contamination of impurities and cost, and further, substrate damage occurs, and it is not necessary to add an excessive amount more than necessary.

The amount of 4AAP added can be appropriately selected in consideration of each specific measurement system.
Generally 0.1 to 20 mM, preferably 0.5 to 10 m
It is good if it is M. If it is less than 0.1 mM, a sufficient enzymatic reaction does not occur. Although there is no problem in measurement even if it exceeds 20 mM, it is not necessarily advantageous in view of the problem of mixing impurities and the cost, and it is not necessary to add an excessive amount more than necessary.

The buffer solution and its pH are both optimum for the reaction of XOD, PNP and POD with both the first reagent and the second reagent, and have good storage stability at pH 5.0 to pH 9.0, especially pH 6.0. -PH 8.0 is preferable, and it is preferable to use a buffer solution having a buffering capacity at this pH. Specifically, PI
PES [piperazine-N ', N'-bis (2-ethanesulfonic acid)], BES [N, N-bis (2-hydroxyethyl) -2-aminoethanesulfonic acid], HEPES
Good buffer solutions such as [N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid] can be used. In addition, any buffer solution having a buffering ability in the above pH range may be used as long as it has no problem in reactivity or stability.

When ESPT is added to the first reagent in order to eliminate the endogenous xanthine in the sample in advance, the addition amount thereof can be appropriately selected in consideration of each specific measurement system. 0.5 to 50 mM, preferably 1 to
It may be 10 mM. If it is less than 0.1 mM, a sufficient enzymatic reaction does not occur. Although there is no problem in measurement even if it exceeds 20 mM, it is not necessarily advantageous in view of the problem of mixing impurities and the cost, and it is not necessary to add an excessive amount more than necessary.

When catalase is added to the first reagent and ESPT is added to the second reagent, ESPT may be added to the second reagent under the same conditions as when adding ESPT to the first reagent. On the other hand, the origin of catalase is not particularly limited, and catalase derived from animals or bacteria can be used. The addition amount can be appropriately selected in consideration of each specific measurement system, but generally 1 to 100 U / ml,
It is preferably 5 to 50 U / ml. 1 U / ml
If it is less than this, sufficient enzyme activity cannot be obtained. 100 U /
Although there is no problem in measurement even if it exceeds ml, it is not necessarily advantageous from the viewpoint of the problem of mixing impurities and the cost, and it is not necessary to add an excessive amount more than necessary.

The liquid reagent for measuring inorganic phosphorus according to the present invention having the above-mentioned structure can maintain stability for a sufficiently long period in the above-mentioned mode. When the stabilization method was examined, oxo acid or its salt, a chelating agent such as ethylenediaminetetraacetic acid disodium (EDTA2Na), or an ethylenediaminetetraacetic acid zinc complex (EDT).
It has been found that the inclusion of a metal-chelate compound such as A-Zn) can stabilize XOD.

Also in the prior art, for example, Japanese Unexamined Patent Publication No.
Japanese Patent No. 335887 discloses a method for stabilizing XOD. That is, it is described that XOD is stabilized by a salt of a metal (including a complex salt) selected from the group consisting of iron, copper, cobalt and manganese and / or a metal chelate compound thereof. But this method
This is a stabilization method using XOD derived from buttermilk, which is different from the stabilization conditions for XOD derived from microorganisms. On the other hand, in the XOD derived from microorganisms, in addition to the metal chelate compound of the metal selected from the group consisting of iron, copper, cobalt and manganese, the metal chelate of the metal selected from the group consisting of zinc, magnesium and calcium. Depending on the compound, a suitable stabilizing effect can be obtained.

When the microorganism-derived XOD is used in the present invention, its stabilizing agent is specifically oxo acid;
Oxonates, such as potassium oxonate or ammonium oxonate; chelating agents, such as ethylenediaminetetraacetic acid (EDTA), 1,2-cyclohexanediaminetetraacetic acid (CyDTA), sarcosine diammonium salt (DTCS), nitrilotripropionic acid. (NTP),
Iminodiacetic acid (IDA) or nitrilotriacetic acid (N
TA) or salts thereof, such as disodium ethylenediaminetetraacetate (EDTA2Na) and disodium nitrilotriacetate (NTA2Na); or metal-chelating compounds (ie, the above chelating agents and iron, copper, cobalt, manganese, zinc). , A compound with a metal selected from the group consisting of magnesium and calcium), for example, ethylenediaminetetraacetic acid zinc complex (EDTA-Zn), 1,2
-Cyclohexanediaminetetraacetic acid calcium complex (Cy
DTA-Ca) and the like can be used alone or in combination.

The amount of these XOD stabilizers added can be appropriately selected in consideration of each specific measurement system.
Generally 0.1-100 mM, preferably 0.2-20
It may be mM. If it is less than 0.1 mM, a sufficient stabilizing effect cannot be obtained. Even if it exceeds 100 mM, it does not hinder the stabilizing effect, but it is not necessarily advantageous in view of the problem of mixing impurities and the cost, and it is not necessary to add an excessive amount more than necessary. XO derived from buttermilk
D is an unstable enzyme, and is described in JP-A-4-335887.
Even if the XOD stabilization method described in the publication is used, it is not possible to obtain the stability required to complete a liquid reagent that can be stored for a long period of time.

When the stabilization method was similarly examined for PNP, bovine serum albumin (BSA) can be used as a stabilizer for microbial PNP. The amount of the PNP stabilizer added can be appropriately selected in consideration of the individual specific measurement system, but is generally 0.1 to 100 g / liter, preferably 1 to 10 g / liter.
It should be liters. If it is less than 0.1 g / liter, a sufficient stabilizing effect cannot be obtained. 100 g /
Even if it exceeds liter, there is no problem in stabilizing effect,
It is not always advantageous in terms of the problem of mixing impurities and the cost, and it is not necessary to add an excessive amount more than necessary.

In addition to the above-mentioned components, a preservative such as NaN ₃ and a stabilizer for POD (for example, ascorbate oxidase) can be appropriately added to the first reagent and / or the second reagent. .

[0028]

With the above-configured reagent for measuring inorganic phosphorus according to the present invention, H ₂ O ₂ is produced from the inorganic phosphorus in the sample by the action of PNP and XOD in the presence of inosine, and this H ₂ O _{2 is produced.} 4AAP and ESP in the presence of POD
An oxidative condensation reaction is performed with T to form a quinoid pigment. The amount of inorganic phosphorus can be determined by colorimetrically measuring this dye. Furthermore, the liquid reagent of the present invention can be stored for a long period of time, and is extremely easy to handle in the clinical laboratory field.

[0029]

The present invention will be described in detail below with reference to examples, but these do not limit the scope of the present invention. Example 1 (1) Preparation of Reagents First reagents A to D and second reagent A of the present invention having the following compositions were prepared. First reagent A: 50 mM PIPES buffer (pH 6.
8) XOD 16 U / ml PNP 2 U / ml POD 10 U / ml ESPT 5 mM First reagent B: BSA added to the first reagent A at 2 mg / ml. First reagent C: potassium oxonate 5 mM in the first reagent A,
EDTA-Zn added at 0.5 mM. First reagent D: BSA added to the first reagent A at 2 mg / ml, potassium oxonate 5 mM, and EDTA-Zn at 0.5 mM. Second reagent A: 50 mM PIPES buffer (pH 6.
8) Inosine 3.7 mM 4AAP 1 mM

(2) Stability test procedure In the above combination, 0.2 ml of each of the first reagents A to D was added to 5 μl of control serum having a known inorganic phosphorus content, and 37
Heated at 0 ° C for 5 minutes. Second reagent A 0.2 ml
Was added and reacted at 37 ° C. for 5 minutes, and the absorbance of the reaction solution at a wavelength of 600 nm was measured. at the same time,
The same operation was performed using physiological saline instead of serum, and the value at that time was used as a blank value. Separately, an aqueous solution of monopotassium phosphate (5 mg / ml) was prepared as a standard, and the same operation was performed to determine the amount of inorganic phosphorus in the control serum. Also, store each reagent at 10 ° C, and after 2 months, 4 months,
After 6 months, 9 months and 12 months, the same operation was performed using the same control serum as above, and the amount of inorganic phosphorus was determined. The standard at this time was calculated by using the absorbance measured immediately after preparation. The obtained results are shown in FIG. According to the reagent of the present invention (combination of the first reagent A to D and the second reagent A),
Very little variation in inorganic phosphorus measurement values after long-term storage,
It can be confirmed that stable performance is maintained for a long time.

Comparative Example For comparison, a combination a of a first reagent a and a second reagent a (comparative example 1) and a combination b of a first reagent b and a second reagent b (comparison) having the following compositions were used. Example 2) was prepared. (A) First reagent a: 50 mM PIPES buffer (p
H6.8) XOD 16 U / ml POD 10 U / ml ESPT 5 mM Second reagent a: 50 mM PIPES buffer (pH 6.
8) Inosine 3.7 mM PNP 2U / ml 4AAP 1 mM (b) First reagent b: 50 mM PIPES buffer (p
H6.8) XOD 16U / ml POD 10U / ml ESPT 5mM Inosine 3.7mM Second reagent b: PNP 2U / ml 4AAP 1mM The stability test was carried out in the same manner as in Example 1 above. The results are shown in Fig. 1.

[0032]

INDUSTRIAL APPLICABILITY The reagent for measuring inorganic phosphorus of the present invention can be stably stored in a liquid state in a dark place or a bright place at room temperature or low temperature for a long period (at least about one year). Therefore, it should be stored for a long time at the site where clinical tests are carried out, and there is no need for a lysing operation when used.
It can be applied as it is to an automatic analyzer.

[Brief description of drawings]

FIG. 1 is a graph showing the stability of a reagent of the present invention and a reagent for comparison stored at 10 ° C.

Claims (4)

[Claims] 1. A purine nucleoside phosphorylase,
In a reagent for measuring inorganic phosphorus containing xanthine oxidase, peroxidase, inosine, 4-aminoantipyrine and N-ethyl-N-sulfopropyl-m-toluidine, a first reagent containing at least xanthine oxidase and purine nucleoside phosphorylase, A reagent for measuring inorganic phosphorus, comprising a second reagent containing at least inosine, each of which is a liquid reagent. 2. The reagent for measuring inorganic phosphorus according to claim 1, wherein the first reagent further contains N-ethyl-N-sulfopropyl-m-toluidine. 3. The reagent for measuring inorganic phosphorus according to claim 1, wherein the first reagent further contains catalase and the second reagent further contains N-ethyl-N-sulfopropyl-m-toluidine. 4. The inorganic phosphorus according to claim 1, wherein the first reagent further contains oxonic acid, oxonate, a chelating agent, a metal-chelating compound and / or bovine serum albumin. Measuring reagent.