Abstract: The present invention relates to an enzyme immunoassay method for assaying calcium ion, including putting calcium-dependent glutamate dehydrogenase, namely glutamate dehydrogenase (GLDH) never expressing its activity in the absence of calcium ion, in contact to the calcium ion in a sample to assay the enzyme activity of the GLDH, the activity changing depending on the calcium ion concentration in the sample; and the invention also relates to an assay reagent for use in the same. Because the reagent is very stable in a solution state under storage, the reagent can be incorporated in a liquid reagent. Thus, the calcium in a biological material or other samples can be assayed in a simple and accurate manner.

Abstract: The present invention relates to an enzyme immunoassay method for assaying calcium ion, including putting calcium-dependent glutamate dehydrogenase, namely glutamate dehydrogenase (GLDH) never expressing its activity in the absence of calcium ion, in contact to the calcium ion in a sample to assay the enzyme activity of the GLDH, the activity changing depending on the calcium ion concentration in the sample; and the invention also relates to an assay reagent for use in the same. Because the reagent is very stable in a solution state under storage, the reagent can be incorporated in a liquid reagent. Thus, the calcium in a biological material or other samples can be assayed in a simple and accurate manner.

Abstract: The invention provides an ammonia elimination reagent in solution, comprising a thermo-resistant isocitrate dehydrogenase with prominent stability under conditions at high alkaline pHs. For example, the isocitrate dehydrogenase is preferably derived from the genus Thermus. For an assay system of biological substances generating a reaction product ammonia, an ammonia elimination reagent can be prepared by selecting and using the enzyme; the resulting ammonia elimination reagent can be stored in solution; additionally, the assay system can be designed in combination with both the coenzymes NAD+ and NADP+. The ammonia elimination reagent is novel and can eliminate ammonia in an extremely short time.

Abstract: The present invention provides a process for mass producing recombinant, thermostable GLDH at a low cost. The invention also provides a process for mass producing recombinant, thermostable GLDH at a low cost, by culturing a transformant without using a drug such as IPTG. The invention further provides thermostable GLDH which can use more stable NADH as a coenzyme in an ammonia assay reagent.

Abstract: The present invention provides a gene encoding the type B subunit protein of avian lactate dehydrogenase. The gene encoding the type B subunit protein of avian lactate dehydrogenase of the present invention is obtained by plaque hybridization or the like from a cDNA library derived from avian heart muscle and encodes the type B subunit protein of avian lactate dehydrogenase having an amino acid sequence shown as SEQ ID NO. 2.

Abstract: Chlorine and calcium ions are measured in a biological sample using a maltose derivative having a chromogenic group at the reducing end. These ions are accurately measured in biological samples such as blood and urine without influence of amylase that may be present in such samples.

Abstract: The present invention relates to a hexokinase that is stable in solution whether in the presence or the absence of glucose. The present enzyme is obtained from a culture of the thermophilic yeast, Kluyveromyces. It can be used for determination of ATP and glucose, and for determination of a biological component which produces ATP or glucose (e.g. creatine kinase).

Abstract: The invention relates to an ammonia elimination reagent for use in an enzymatic assay of a biological substance which produces ammonia as the reaction product. The reagent is an alkaline solution of pH 9 to 11 and contains Sulfolobus-derived thermostable isocitrate dehydrogenase, 2-oxoglutaric acid, a reducing coenzyme, isocitric acid, glutamate dehydrogenase, and a divalent metal salt. The reagent can be stored in solution and has excellent stability under conditions of alkaline pHs.

Abstract: The present invention provides a gene encoding the type B subunit protein of avian lactate dehydrogenase. The gene encoding the type B subunit protein of avian lactate dehydrogenase of the present invention is obtained by plaque hybridization or the like from a cDNA library derived from avian heart muscle and encodes the type B subunit protein of avian lactate dehydrogenase having the sequences shown as SEQ ID NO. 1 or 2.

Abstract: This invention relates to an enzyme assay for quantitative analysis of biochemical substances using NAD(P)-NAD(P)H system and utilizing hydrogen peroxide, in which isocitric acid, metal ions and isocitrate dehydrogenase are previously added to a test sample, thereby consuming the endogenous substances that interfere the analysis, and at the same time regenerating NAD(P)H reduced.The isocitrate dehydrogenase is then inactivated by addition of a chelating agent, an enzyme or substrate that generates hydrogen peroxide as reaction product is added simultaneously or thereafter, and the amount of hydrogen peroxide thus formed is measured.Biochemical substances that generate hydrogen peroxide as reaction product can be correctly analyzed by this method with no adverse effect of endogenous substances because these interfering substances have been removed prior to measurement.

Abstract: Urea, creatinine, creatine, triglycerides, or the like in a specimen can be accurately determined by terminating an isocitrate dehydrogenase reaction by addition of a chelating agent in a system wherein NADP.sup.+ formed from NADPH is reproduced into NADPH in the conjoint presence of an isocitrate, metallic ions such as magnesium or manganese ions, and isocitrate dehydrogenase in assaying a substance by means of a reaction of NADPH to NADP.sup.+.

Abstract: Urea, creatinine, creatine, triglycerides, or the like in a specimen can be accurately determined by terminating an isocitrate dehydrogenase reaction by addition of ATP and/or a chelating agent in a system wherein NAD.sup.+ formed from NADH is reproduced into NADH in the conjoint presence of an isocitrate, metallic ions such as magnesium or manganese ions, and isocitrate dehydrogenase in assaying a substance by means of a reaction of NADH to NAD.sup.+.

Abstract: A group of compounds having the following general formula can be obtained by reacting chromoprotein and organic acid: ##STR1## wherein X is a chromophore, P is a protein, NH.sub.2 is mainly .epsilon.-amino group of lysine, n is a positive integer of 1 to 18, and m is a positive integer in the relation of m.ltoreq.n. This compound group has one to eighteen organic acids bonded thereto, and shows various isoelectric points in accordance with the number of the organic acids, but the respective isoelectric points are maintained constant. If such compounds each having an individual isoelectric point, are used as isoelectric point markers, it is possible to recognize accurately the position of isoelectric point only by a visual operation.