Coulter Electronics, Inc.

Mathew M Madappally

Giovanni Bucolo

Gerald E Jaffe

An improvement in a method for determining a substance present in a biological fluid by oxidizing a compound produced in the course of the determination in the presence of a dehydrogenase enzyme with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide in an amount proportional to the content of the substance in the fluid, which fluid also contains an endogenous material which or a derivative of which produced during the determination likewise is oxidized in the presence of the enzyme with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide, thereby interfering with the determination, which improvement involves first carrying out the oxidation-reduction reaction of the endogenous material or its derivative, then oxidizing the resulting reduced beta-nicotinamide adenine dinucleotide in the presence of lactate dehydrogenase with the simultaneous reduction of pyruvate to lactate, thereafter inhibiting the lactate dehydrogenase enzymatic activity, and thereafter producing a quantity of the aforesaid compound produced in the course of the determination for conducting the oxidation-reduction reaction therewith without interference caused by the endogenous material or the lactate dehydrogenase. Substances which may be determined include alpha-amylase, transaminases, and triglycerides. A two-reagent combination is employed for the determination.

Method for determining a substance in a biological fluid and reagent

An improvement in a method for determining glutamate oxalacetate transaminase or glutamate pyruvate transaminase present in a biological fluid, in which method L-glutamate is produced from alpha-ketoglutarate by transamination in the presence of the transaminase in the fluid, and the L-glutamate is oxidatively deaminated in the presence of glutamate dehydrogenase with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide in an amount proportional to the content of the transaminase in the fluid, such fluid also containing an endogenous substance which is oxidized in the presence of glutamate dehydrogenase with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide, thereby interfering with the determination. The improvement for obviating the interference caused by the endogenous substance includes oxidizing the endogenous substance in the presence of glutamate dehydrogenase with the simultaneous reduction of beta-nicotinamide adenine dinucleotide, oxidizing the reduced beta-nicotinamide adenine dinucleotide in the presence of lactate dehydrogenase with the simultaneous reduction of pyruvate to lactate, thereafter inhibiting the lactate dehydrogenase activity, and thereafter producing a quantity of L-glutamate from alpha-ketoglutarate by the aforesaid transamination for oxidative deamination thereof and simultaneous production of reduced beta-nicotinamide adenine dinucleotide in an amount proportional to the content of the transaminase in the fluid. A reagent combination is employed for the determination.

Method for determining a transaminase in a biological fluid and reagent

A colorimetric method for the determination of gamma-glutamyl transpeptidase enzyme activity in a biological fluid comprises catalytically reacting the enzyme in the fluid with a substrate of a water-soluble salt of a compound selected from the group consisting of L-gamma-glutamyl-3-sulfoanilide and L-gamma-glutamyl-4-sulfoanilide in aqueous solution to produce the corresponding aniline sulfonic acid salt as a cleavage product, diazotizing the cleavage product, and coupling the diazotized product with a coupling compound to produce a dye having a color intensity proportional to the enzyme activity.

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Cooper City, FL, United States of America

Mathew M Madappally