JPH11196A - Dry analytical element for quantitatively determining creatine kinase mb isozyme - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dry analytical element for quantitatively determining a creatine kinase MB isozyme, small in decrease of sensitivity even in a normal temperature preservation and thereby capable of being preserved at normal temperature. SOLUTION: This dry analytical element is a dry analytical element for determining a creatine kinase MB isozyme, having a detecting reagent layer containing an antibody specifically inhibiting M subunit activities of the creatine kinase, creatine phosphate capable of forming adenosine triphosphate(ATP) in the presence of the creatine kinase MB isozyme, adenosine diphosphate(ADP), a buffer compound for providing a pH environment for producing the ATP, and further an indicator composition for forming a compound detectable by a spectroscopic measuring method by reacting the indicator with the formed ATP, and laminated on a supporter, and the indicator composition includes hexokinase, reduced nicotinamide adenine dinucleotide (phosphate) [NAD (P)] and glucose-6-phosphate dehydrogenase, and does not include the glucose of an amount required for manifesting the function of the indicator composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dry analytical element for quantifying MB isozyme of creatine kinase.

[0002]

2. Description of the Related Art Diagnosis of progressive muscular atrophy, dermatomyositis, myocardial infarction, etc. is determined by quantifying creatine kinase (CK, also called creatine phosphokinase (CPK)) contained in blood collected from a subject. It has been known for some time that it is possible and has been used in clinical tests. In addition, creatine kinase (CK) includes creatine kinase MM (CKMM) and creatine kinase MB.
(CKMB) and creatine kinase BB (CKB
It is also known that there are three isozymes, B), and that CKMM is mainly present in skeletal muscle, CKMB is mainly present in myocardium, and CKBB is mainly present in brain and spinal cord. Furthermore, CKMB is excreted from the myocardium into the blood when myocardial infarction occurs, and as a result,
It has also been found that the amount of CKMB in blood increases. Therefore, quantification of CKMB in the blood of a subject is a powerful means for examining the occurrence of myocardial infarction.

[0003] As described above, in clinical examinations, quantification of creatine kinase (ie, quantification of total creatine kinase) and / or quantification of creatine kinase MB isozyme may lead to progressive muscular atrophy in a subject.
Since powerful clues can be obtained for the diagnosis of dermatomyositis, myocardial infarction, and the like, studies on such quantification methods have been conducted, and high-precision quantification methods have been established at present.

[0004] That is, as a method of measuring creatine kinase, serum or plasma is obtained from blood collected from a subject, and the enzyme activity of creatine kinase contained in the serum or plasma is used to detect creatine kinase by a spectroscopic method. This is a method in which a chemical species that can be produced is quantitatively generated, and the amount of creatine kinase in serum or plasma is quantified from the amount of the generated chemical species. More specifically,
The detection reaction system used in this quantification method can be divided into the following two.

1) Detection reaction system 1 Creatine phosphate (CP) and adenosine diphosphate (AD)
P) and creatine present in a test solution (such as serum or plasma) while adjusting the pH environment of the enzymatic reaction using a buffering compound having a buffering capacity in the pH range of 5.5 to 8.5. By contacting with a kinase (CK) to produce an amount of adenosine triphosphate (ATP) in proportion to the amount of creatine kinase (CK).
TP and glucose (Glu) are converted to hexokinase (H
K) to react with glucose-6-phosphate (G
6P), which is then converted to nicotinamide adenine dinucleotide (phosphate) oxidized form (NAD
(P)) and nicotinamide adenine dinucleotide (phosphate) reduced form (NAD (P)) in the presence of glucose-6-phosphate dehydrogenase (G6PDH).
H), and finally, the amount of NAD (P) H produced is measured by a spectroscopic measurement method, and creatine kinase (CK) is quantified using a separately prepared calibration curve.

Since the accuracy of the spectrophotometric determination of the produced NAD (P) H tends to be insufficient, the NAD (P) H
A method for quantifying creatine kinase in a test solution by further reacting (P) H with a tetrazolium salt to form a formazan dye and quantifying the amount of the formazan dye that has been developed (particularly). Kaisho 63-32
No. 499). The detection reaction system 1 is shown below by a reaction formula.

[0007] CP + ADP → ATP + creatine (in the presence of CK) ATP + Glu → G6P + ADP (in the presence of HK) G6P + NAD (P) → NAD (P) H + 6-phosphogluconic acid (in the presence of G6PDH) ) NAD (P) H + tetrazolium salt → formazan dye + NAD (P)

2) Detection reaction system 2 Creatine phosphate (CP) and adenosine diphosphate (AD)
P) and creatine kinase present in a test solution (such as serum or plasma) while adjusting the pH environment of the enzyme reaction with a buffering compound exhibiting a buffering ability in the pH range of 5.5 to 8.5. CK) to produce an amount of adenosine triphosphate (ATP) that is proportional to the amount of creatine kinase (CK).
Glycerol kinase (HK) with TP and glycerol
To produce L-α-glycerophosphate, and then react this L-α-glycerophosphate with oxygen in the presence of L-α-glycerophosphate oxidase to generate hydrogen peroxide, Finally, the hydrogen peroxide is reacted with the leuco dye to form a blue dye, the amount of the blue dye is measured by a spectroscopic measurement method, and creatine kinase (CK) is prepared using a separately prepared calibration curve. Is a method of quantifying The detection reaction system 2 is shown below by a reaction formula.

CP + ADP → ATP + creatine (in the presence of CK) ATP + glycerol → L-α-glycerophosphate + ADP (in the presence of glycerol kinase) L-α-glycerophosphate + O ₂ → H ₂ O ₂ + dihydroxyaceto Phosphoric acid (in the presence of L-α-glycerophosphate oxidase) H ₂ O ₂ + leuco dye → blue dye + H ₂ O

On the other hand, as described above, since creatine kinase has three types of isozymes, quantification of creatine kinase MB isozyme is not easy. That is, in principle, it is necessary to separate and quantify the MB isozyme from the MM isozyme and the BB isozyme. However, since the BB isozyme is originally present in the brain and spinal cord, its abundance in blood is very small and its presence can be ignored. Therefore, M
Quantification of the B isozyme is possible if the MM isozyme can be separated, but the separation is very difficult. Therefore, instead of separating the MM isozyme in a blood sample containing creatine kinase (such as serum or plasma), a method of inhibiting the activity of the MM isozyme without affecting the activity of the MB isozyme,
A method for realizing substantial MB isozyme separation has already been developed (see Japanese Patent Publication No. 56-19239). In this method, an antibody that completely inhibits the enzymatic activity of MM isozyme of creatine kinase and subunit M in MB isozyme without inhibiting the enzymatic activity of subunit B in creatine kinase MB isozyme prepared in advance is used. . That is, the test solution is first treated with the M-subunit inactivating antibody to limit the activity of creatine kinase to only that attributable to the creatine kinase MB isozyme. By measuring using reaction system 2, creatine kinase M
The B isozyme can be quantified.

[0011] In the previous clinical examination of creatine kinase MB isozyme, a wet method in which a detection reaction is carried out in a reagent solution using the method described above was generally used. However, the quantitative analysis operation by the wet method has a disadvantage that it requires a considerably long time to obtain a result. That is, for example, for myocardial infarction, it is known that the shorter the time from the onset of infarction to the start of treatment, the higher the effect of the treatment is. high. Therefore, a long time from the start of the test to the acquisition of the test result causes a delay in the start of the treatment, which is not preferable.

As a means for obtaining a result of a clinical test in a short time, various dry analytical elements each having a structure in which a reagent layer containing a reagent composition involved in a detection reaction is laminated on a transparent support have been known. . In addition, a dry analytical element for quantifying creatine kinase MB isozyme having a reagent layer containing a reagent composition involved in the above-described creatine kinase MB isozyme test reaction has already been developed and actually used. The configuration of such a dry analytical element for quantifying creatine kinase MB isozyme is described in detail in the following patent publication. JP-A-61-2541
No. 98, JP-A-61-254199, and JP-A-61-260164.

The above-mentioned dry analytical elements for quantifying creatine kinase MB isozyme are excellent analytical tools which can be used for the quantitative analysis of creatine kinase MB isozyme in a short time, but they are practically used after the analytical element is manufactured. However, there is a problem that the storage stability is poor until it is used for quantitative analysis of. That is, it has been found that when each analytical element is stored under normal storage conditions, the sensitivity is reduced within a short period of time after production. Therefore, in order to maintain these dry analysis elements in a good storage state, it was necessary to freeze and store the analysis elements. The necessity of cryopreservation for preservation of such an analysis element means that not only the cryopreservation equipment is required, but also a time delay is likely to occur when starting an actual clinical test. is there.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the low storage stability of a dry analytical element for quantifying creatine kinase MB isozyme which has been known so far. The present invention particularly relates to creatine kinase M, which has a small sensitivity decrease even when stored at room temperature, and thus can be stored at room temperature.
An object of the present invention is to provide a dry analytical element for quantifying B isozyme.

[0015]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a semiconductor device comprising the steps of:
In the presence of creatine kinase MB isozyme, an antibody that specifically inhibits the M subunit activity of creatine kinase, creatine phosphate and adenosine diphosphate, which produce adenosine triphosphate, and for the production of adenosine triphosphate PH 5.5 to 8.
A buffering compound that exhibits buffering capacity in the region of 5,
Furthermore, a dry method for creatine kinase MB isozyme quantification comprising a layer of a creatine kinase MB isozyme detection reagent containing an indicator composition for producing a compound detectable by a spectroscopic measurement method by reaction with the generated adenosine triphosphate. An analytical element, wherein the indicator composition comprises hexokinase, nicotinamide adenine dinucleotide (phosphate) oxidized form, and glucose-6-phosphate dehydrogenase. A dry analytical element for quantifying creatine kinase MB isozyme, which does not contain a necessary amount of glucose.

According to the study of the inventor of the present invention, the low storage stability of the conventional dry analytical element for quantifying creatine kinase MB isozyme is because during the storage thereof, the reagent in the reagent composition is changed to the creatine kinase MB isozyme. (CKMB) was found to be caused by a gradual reaction in the absence of CKMB. In particular, in the detection reaction system 1 described above, even if CK or CKMB does not exist, a phenomenon in which CP and ADP partially react to generate ATP, and that CP and Glu react to generate G6P. Was confirmed. Therefore, this creatine kinase M
Reactions that occur in the absence of the B isozyme result in a significant decrease in analytical accuracy.

For the above reasons, the present inventor has studied for the purpose of suppressing the undesirable reaction that occurs during the storage of the dry analytical element at room temperature as described above. And as a result,
It has been found that, in an analytical element utilizing the above-described detection reaction system 1, by excluding glucose involved in a side reaction during storage of the analytical element from the analytical element, the problematic side reaction can be prevented or suppressed. In order to start the actual detection reaction of the detection reaction system 1, the presence of glucose is necessary, of course. Since glucose brought into the analytical element can be used, it has been found that removing glucose from the indicator composition in the analytical element has no problem in actual quantitative analysis.

Although the above concept can be applied in principle to an analytical element for quantifying creatine kinase (CK), the amount of creatine kinase present in a normal test solution (serum or plasma) is limited to creatine kinase MB. Since the amount of ATP generated by the enzymatic reaction in the presence of a large amount of creatine kinase in the presence of a large amount of creatine kinase is larger than that of the isozyme, the amount of glucose necessary for the subsequent reaction should be sufficiently supplied from the test solution. Therefore, the application of the present invention is not very advantageous in practice. In addition, in the detection reaction system 2, since there is nothing that can be supplied from the test solution due to the nature of the components of the indicator composition, the concept of the present invention cannot be used.

That is, the creatine kinase M of the present invention
The dry analytical element for quantification of B performs quantification of creatine kinase MB isozyme by using an antibody that specifically inhibits the M subunit activity of creatine kinase in combination with the detection reaction system 1 described above. It is characterized in that glucose present in blood is used as glucose required in the detection reaction system 1. That is, it is characterized in that no glucose is introduced into the analysis element, or at least glucose is not introduced to an amount necessary for the progress of the detection reaction system. Although the analytical element of the present invention is an analytical element utilizing the detection reaction system 1, whether or not glucose is introduced as described above,
Alternatively, since at least a large amount of glucose is not introduced, it is possible to avoid or suppress a side reaction that occurs due to the involvement of glucose during storage, thus exhibiting improved storage stability.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the analytical element of the present invention are described below. 1) The dry analytical element for quantifying creatine kinase MB isozyme, wherein the indicator composition further comprises a tetrazolium salt. 2) The dry analytical element for quantifying creatine kinase MB isozyme described above, wherein the indicator composition does not contain glucose. 3) Nicotinamide adenine dinucleotide (phosphate)
The oxidized form is nicotinamide adenine dinucleotide oxidized form (NAD) (ie, without NADP)
The above-mentioned dry analytical element for quantifying creatine kinase MB isozyme. 4) The indicator composition further comprises lactate dehydrogenase (LD)
H) The above-mentioned dry analytical element for quantifying creatine kinase MB isozyme containing an activity inhibitor. 5) The above-mentioned dry analytical element for quantifying creatine kinase MB isozyme, wherein the indicator composition further comprises a lactate dehydrogenase (LDH) activity inhibitor selected from the group consisting of oxaloacetate, oxalic acid, and oxamic acid.

The detection reaction system used in the dry analytical element for quantifying creatine kinase MB of the present invention is the above-mentioned detection reaction system 1. Accordingly, the indicator composition used in the above-described detection reaction system can be used as an indicator composition that produces a compound that can be detected by a spectroscopic measurement method by reacting with adenosine triphosphate. That is, examples of the indicator composition include the following indicator compositions.

1) An indicator composition containing hexokinase, nicotinamide adenine dinucleotide (phosphate) oxidized form, and glucose-6-phosphate dehydrogenase, containing no glucose or containing a trace amount of glucose. 2) An indicator composition containing hexokinase, nicotinamide adenine dinucleotide (phosphate) oxidized form, glucose-6-phosphate dehydrogenase, and tetrazolium salt and containing no glucose or a trace amount of glucose.

The construction of the dry analytical element for quantifying creatine kinase MB isozyme of the present invention and the various reagents constituting the same are already known. Or at least save for not introducing the required amount of glucose,
Various reagents having the same configuration and the same are used. The configuration of such a dry analytical element and examples of reagents are described in detail in the above-mentioned patent publications and publications, and will not be described again here.

In the analysis element of the present invention,
As a buffering compound having a buffering capacity in a pH range of 5.5 to 8.5, which provides a pH environment for adenosine triphosphate production, a conventional dry analytical element for quantifying creatine kinase MB isozyme for this purpose is used. As commonly used Bis-Tris (bis-Tris), imidazole can be used, but it is included in the list of buffering compounds having a sulfonic acid group, in particular, Good's buffer,
It is preferable to use a compound having a sulfonic acid group in the molecular structure. That is, Good's buffering agents include those having a sulfonic acid group and those not having a sulfonic acid group, and the buffering compounds advantageously used in the present invention include sulfonic acid groups among them. It has a buffering compound. The use of the buffering compound having a sulfonic acid group further effectively suppresses the occurrence of side reactions during storage of the analytical element. In addition, about Good's buffer (or also called Good's buffer), for example, "Chemical Dictionary" (Morikita Publishing Co., Ltd., published in 1981), "Chemical Dictionary" (Tokyo Chemical Dojin, 198
(Published 9 years), and further, there is a detailed description in many books on clinical test reagents.

The buffering compounds belonging to Good's buffer and suitable for use in the dry analytical element of the present invention include:
TES, TAPSO, MOPSO, MES, DIPS
Compounds named O, HEPES, HEPSO can be mentioned. Among these compounds, TE
Compounds named S, TAPSO, MOPSO, and MES are preferred. Particularly preferred is TES
And TAPSO.

The amount of the buffering compound used in the analytical element of the present invention is not particularly limited. In other words, by referring to the general mode of use of Good's buffer, a suitable amount can be easily determined by using a general method for determining the amount of use such as test use with varying amounts of use. can do. The buffering compound may be used in combination of two or more kinds. For example, the buffering compound may be used in combination with a buffering compound having no sulfonic acid group or another buffering composition.

The reagent layer of the analytical element of the present invention has LDH
It is desirable to introduce a compound capable of inhibiting the expression of the enzyme activity of (lactate dehydrogenase). That is, according to the research of the present inventor, when glucose is not introduced into the analytical element or glucose is not introduced until the required amount is reached, nicotinamide adenine dinucleotide (phosphate) oxidized form (NADP) ), But not oxidized nicotinamide adenine dinucleotide (N
It is desirable to use AD), but when NAD is used, the analytical value of CKMB tends to fluctuate depending on the amount of LDH (lactate dehydrogenase) generally present in the test solution, which lowers the analytical accuracy. Is known. Therefore, it is desirable to introduce a compound capable of inhibiting or suppressing the LDH enzyme activity (eg, oxaloacetate, oxalic acid, and oxamic acid) into the reagent-containing layer of the analysis element.

The operation of quantitative analysis of creatine kinase MB isozyme (CKMB) using a dry analytical element for quantifying creatine kinase MB isozyme is described in the aforementioned patent publications and patent publications.
It is already known that C using the dry analytical element of the present invention can be used.
The KMB quantitative analysis operation can be performed according to the same operation as those described above. Next, examples of the present invention and comparative examples will be described.

[0029]

[Example 1] Production of analytical element for CKMB quantification without introduction of glucose Transparent polyethylene terephthalate film (thickness 180)
μm) was subjected to a hydrophilic treatment, and a coating solution having the following composition was applied on the treated surface and dried to form an indicator layer having a dry layer thickness of 12 μm.

Deionized gelatin 200 g Water 1100 g 5% nonionic surfactant aqueous solution 80 g Nitrotetrazolium blue 10 g

After the indicator layer is moistened with a solution containing a gelatin crosslinking agent (about 30 g / m ² ), a tricot knit made of a spun yarn of polyethylene tetraphthalate is pressed on the indicator layer, dried and developed. Layers. Next, a coating solution having the following composition was applied on the surface of the spread layer at a coating amount of 130 g / m ² and dried.

46.6 g of water 20 g of anti-human CK-M goat antibody solution (a solution capable of inhibiting 50% or more of 2,000 U / L CKMM at a final dilution of 1500 times) 10% nonionic surfactant aqueous solution 9 g 15% aqueous solution of polyacrylamide 33.8 g (average molecular weight 37,000) 20% aqueous magnesium chloride solution 8.7 g ethylenediaminetetraacetic acid / 2Na salt 0.5 g creatine phosphate (CK) 1.3 g adenosine-5'-diphosphate ^{(ADP) 0.3g P 1, P} 5 - di (adenosine-5') penta phosphate (AP5A) 0.25 g adenosine 5'-monophosphate (AMP) 1.2 g N-acetyl -L- cysteine 0. 1 g Nicotinamide adenine nucleotide oxidized form (NAD) 0.6 g Oxaloacetic acid 0.07 g N-tris (hydroxymethyl) methyl-2-aminoethanesulfonic acid (TES) 5.1 g 1N NaOH 10.0 g Diaphorase 1500 U Glucose-6-phosphate dehydrogenase 14000 U Hexokinase (HK) 19400 U Ascorbate oxidase 5000 U

Finally, the laminate formed above, in which the indicator layer and the reaction reagent-containing developing layer are laminated on the support, is
It was cut into a size of 2 mm x 12 mm to obtain an analytical element for quantifying CKMB containing no glucose. When the distribution of the reagent in the obtained analytical element for CKMB quantification was examined, it was confirmed that most of the nitrotetrazolium blue introduced into the indicator layer had moved to the developing layer.

Comparative Example 1 CKM Containing Glucose
Manufacture of analytical element for B quantification 0.62 g of glucose in the coating liquid applied to the surface of the spreading layer
CKMB quantitative analysis element was obtained in the same manner as in Example 1 except that was added.

[Evaluation of analytical element for quantification of CKMB: generation of ATP during storage] The analytical elements obtained in Example 1 and Comparative Example 1 were subjected to storage under conditions of 45 ° C. and 11% RH, respectively.
After storing for a day, a trace amount of water was spotted on the surface of the developing layer of each analytical element, and incubated at 37 ° C. for 6 minutes.
Next, at a wavelength of 540 nm, the coloration generated in each analytical element was measured. In parallel, the same color test was performed on the analytical elements of Example 1 and Comparative Example 1 immediately after the production. The coloration of each analytical element found by this measurement is shown in Table 1 below.

[0036]

[Table 1] Table 1 ──────────────────────────────────── Analytical element Glucose coloring (optical Density: OD) Analytical element immediately after production Analytical element stored for 1 day ──────────────────────────────────── Example 1 not introduced 0.50 0.52 Comparative Example 1 introduced 0.50 0.61 ──────────────────────────── ────────

From the results shown in Table 1, the by-product of ATP in the absence of creatine kinase MB isozyme was effectively suppressed in the glucose-free analytical element employed in the present invention. It is clear that.

Example 2 Production of CKMB Quantitative Analysis Element Containing No Glucose and Oxaloacetic Acid CKMB was prepared in the same manner as in Example 1 except that oxaloacetic acid was completely removed from the coating liquid component applied to the surface of the spreading layer. An analytical element for quantification was obtained.

[Effect of LDH Content in Test Liquid] Each of the analytical element obtained in Example 1 and the analytical element obtained in Example 2 was stored at 35 ° C. and 11 RH% for 10 days. After that, a sample having a constant CKMB content and no LDH and a sample having an LDH content of 1000 U / L were spotted on each analytical element. After evaporating water from the analytical element on which the sample was spotted, incubation was performed at 37 ° C., and then spectroscopic measurement was performed at a wavelength of 540 nm at 2 minutes and 5 minutes after the start of incubation, and the sample was prepared in advance. The CKMB amount was quantified by a reaction rate method with reference to the calibration curve. The results are shown in Table 2 below.

[0040]

[Table 2] Table 2 分析 Analysis element Sample CKMB measurement value ( (CKMB amount) Sample without LDH Sample with LDH ──────────────────────────────────── Example 15U / L 5U / L 7U / L Example 2 5U / L 5U / L 55U / L ────────

From the results shown in Table 2 above, in order to quantify CKMB in a CKMB-containing specimen containing a considerable amount of lactate dehydrogenase (LDH), an inhibitor of LDH activity was applied to an analytical element for quantifying CKMB. It turns out that the introduction of is effective.

[0042]

According to the present invention, when glucose is used in the detection reaction system of a dry analytical element for quantitative analysis of creatine kinase MB isozyme (CKMB), the glucose is not introduced into the analytical element in advance, or the amount of introduced glucose is very small. By stopping, the preservation of the analytical element for quantification of CKMB is remarkably improved, and the necessity of the cryopreservation of the analytical element which has been indispensable when preserving the dry analytical element for quantitative analysis of the conventional CKMB is eliminated. This is very advantageous in practical use. LDH (lactate dehydrogenase)
When using a sample such as serum containing a large amount of
It is preferable to introduce an LDH activity inhibiting compound into a dry analytical element for MB quantification.

Claims (6)

[Claims] 1. A creatine phosphate and adenosine diphosphate, which produce adenosine triphosphate in the presence of an antibody that specifically inhibits the creatine kinase M subunit activity, a creatine kinase MB isozyme,
It contains a buffering compound exhibiting a buffering capacity in a pH range of 5.5 to 8.5, which provides a pH environment for the production of adenosine triphosphate, and is further subjected to spectroscopy by reaction with the generated adenosine triphosphate. Kinase MB isozyme quantification dry analytical element obtained by laminating a creatine kinase MB isozyme detection reagent layer containing an indicator composition that produces a compound detectable by a quantitative measurement method, wherein the indicator composition comprises hexokinase Nicotinamide adenine dinucleotide (phosphate) oxidized form and glucose-6-phosphate dehydrogenase, but does not contain glucose in an amount required for expression of the function of the indicator composition. Dry analytical element for quantification of creatine kinase MB isozyme. 2. The dry analytical element for quantifying creatine kinase MB isozyme according to claim 1, wherein the indicator composition further comprises a tetrazolium salt. 3. The dry analytical element for quantifying creatine kinase MB isozyme according to claim 1, wherein the indicator composition does not contain glucose. 4. The dry analytical element for quantifying creatine kinase MB isozyme according to any one of claims 1 to 3, wherein the nicotinamide adenine dinucleotide (phosphate) oxidized form is nicotinamide adenine dinucleotide oxidized form. . 5. The dry analytical element for quantifying creatine kinase MB isozyme according to claim 4, wherein the indicator composition further comprises a lactate dehydrogenase activity inhibitor. 6. The dry analytical element for quantifying creatine kinase MB isozyme according to claim 4, wherein the indicator composition further comprises a lactate dehydrogenase activity inhibitor selected from the group consisting of oxaloacetate, oxalic acid, and oxamic acid.