Abstract: The present invention provides a reagent for the enzymatic determination of an enzyme substrate, containing a system for the determination of the substrate, which comprises at least one enzyme, at least one buffer substance and at least one indicator substance and optionally contains adjuvants, wherein the reagent contains a definite amount of the enzyme substrate in an insufficient amount with regard to the substrate determination capacity of the system for the determination of this substrate.The present invention also provides a process for the enzymatic determination of an enzyme substrate in the presence of disturbing substances which can react with the substrate itself or with an intermediate or end product of the indicator reaction, wherein, before the addition of the sample to be investigated, a definite amount of the substrate is first reacted with the reagent until reaction is complete, whereafter the sample to be determined is added.

Abstract: Cholesterol is determined by incubating a sample suspected of containing cholesterol in an aqueous medium with cholesterol oxidase and determining either the oxygen consumption, the hydrogen peroxide formed, or cholestenone, as a measure of the initial cholesterol content; reagent compositions comprising cholesterol oxidase and a system for the determination of H.sub.2 O.sub.2 or for the determination of cholestenone are provided.

Abstract: Cholesterol is determined utilizing cholesterol oxidase, and optionally cholesterol esterase to cleave bound cholesterol, in the presence of peroxidase, p-amino-phenazone, a surface-active agent and phenol, the improvement comprising employing an alkanol of up to 4 carbon atoms in the test composition or sample to substantially overcome test error and deviations due to turbidity formation.

Abstract: Cholesterol oxidase free of unstabilizing residual traces of detergent is activated by adding to the cholesterol oxidase, before use thereof, at least one surface-active compound with lipophilic and hydrophilic properties. Diagnostic agents for determining cholesterol comprising cholesterol oxidase, a hydrogen peroxide detection system, a buffer, and at least one surface-active compound having lipophilic and hydrophilic properties are provided.

Abstract: Enzyme preparations, particularly enzyme preparations containing organic sulfhydryl compounds for activation, are stabilized by means of a stabilizing agent comprising oxypolygelatine, especially oxypolygelatine having an average molecular weight of from 10,000 to 50,000.

Abstract: L-lactate is quantitatively determined by the reaction thereof with nicotinamide-adenine-dinucleotide (NAD) in the presence of lactate dehydrogenase (LDH) with the formation of reduced NAD (NADH) and pyruvate, reaction of the latter with glutamate in the presence of glutamate-pyruvate-transaminase (GPT) with the formation of alanine and .alpha.-ketoglutarate in alkaline buffered solution and measurement of the NADH formed, wherein the reaction is carried out in the presence of at least 0.4 mol/liter of carbonate or bicarbonate.

Abstract: Triglycerides are determined by enzymatic saponification with lipase in a buffer in the presence of a carboxylesterase and an alkali metal or alkaline earth metal (10-15 carbon atom) alkyl sulfate, in the additional presence of a compound of the general formula RO(CH.sub.2 CH.sub.2).sub.n H, in which R is alkyl or alkenyl containing 14 to 20 carbon atoms and n is a number of from 7 to 20; this determination prevents turbidity and does not disadvantageously influence enzyme activity.

Abstract: .gamma.-Glutamyl-4-nitroanilide compounds of the formula ##STR1## wherein R is a .gamma.-glutamyl radical and X is an acid group, and salts of such compounds, are used to determine .gamma.-glutamyl-transpeptidase by contacting a sample suspected of containing .gamma.-glutamyltranspeptidase with said compound and glycylglycine and determining the liberation of the resulting p-nitro-aniline compound as a measure of the .gamma.-glutamyltranspeptidase activity initially present in the sample.

Abstract: .gamma.-Glutamyl-4-nitroanilide compounds of the formula ##SPC1##Wherein R is a .gamma.-glutamyl radical and X is an acid group, and salts of such compounds, are used to determine .gamma.-glutamyltranspeptidase by contacting a sample suspected of containing .gamma.-glutamyltranspeptidase with said compound and glycyl-glycine and determining the liberation of the resulting p-nitroaniline compound as a measure of the .gamma.-glutamyltranspeptidase activity initially present in the sample.

Abstract: .gamma.-Glutamyl-4-nitroanilide compounds of the formula ##SPC1##Wherein R is a .gamma.-glutamyl radical and X is an acid group, and salts of such compounds, are used to determine .gamma.-glutamyltranspeptidase by contacting a sample suspected of containing .gamma.-glutamyltranspeptidase with said compound and glycylglycine and determining the liberation of the resulting p-nitroaniline compound as a measure of the .gamma.-glutamyltranspeptidase activity initially present in the sample.

Abstract: The new enzyme steroid-.DELTA.-isomerase is provided, as well as a process for producing same, comprising digesting a micro-organism containing said isomerase, extracting same by destruction of the cell wall with a buffer solution containing a non-ionic surfactant, centrifuging the resulting mass and discarding the precipitate, applying the extract to an anion exchanger, eluting the enzyme with a buffer solution containing a non-ionic surfactant, heating the eluate, separating the precipitate and isolating the enzyme therefrom from the supernatant.