Abstract: To provide a method for simply and precisely measuring cholesterol (LDL-C) in low-density lipoprotein in a sample without use of any surfactant having an alkylphenol structure, in terms of environmental friendliness. A method for measuring LDL-C in a sample, the method comprising: reacting the sample with (i) a combination of cholesterol ester hydrolase and cholesterol oxidase or (ii) a combination of cholesterol ester hydrolase, an oxidized coenzyme and cholesterol dehydrogenase, in an aqueous solvent which comprises: [a] one or more surfactants selected from the group consisting of a polyoxyethylene alkyl ether and a polyoxyethylene polyoxypropylene alkyl ether; and [b] a polyoxyethylene polyoxypropylene copolymer; and which does not comprise any surfactant having an alkylphenol structure; and measuring a substance formed or consumed in the reaction.

Abstract: The present invention provides a method for stabilizing a cholesterol oxidase, a method for preserving a cholesterol oxidase, and a stabilized composition of cholesterol oxidase. A method for stabilizing a cholesterol oxidase and a method for preserving a cholesterol oxidase which comprises allowing the cholesterol oxidase to coexist with an ?-keto acid in an aqueous medium, and, a stabilized composition of cholesterol oxidase which comprises the cholesterol oxidase being allowed to coexist with an ?-keto acid in an aqueous medium. The method for stabilizing a cholesterol oxidase, the method for preserving a cholesterol oxidase, and a stabilized composition of cholesterol oxidase according to the present invention are useful for clinical diagnosis such as metabolic syndrome.

Abstract: Provided is a measuring method of a component to be measured in a specimen while suppressing an influence of bilirubin. A measuring method of a component to be measured, comprising converting the component to be measured in the specimen to hydrogen peroxide through an enzymatic reaction, reacting the formed hydrogen peroxide with an oxidative-coloring chromogen in the presence of a peroxidase, and measuring an absorbance of the colored reaction solution to thereby determine the component to be measured, wherein a fatty acid or a salt thereof coexists. The measuring method of a component to be measured in a specimen according to the present invention is useful in clinical diagnosis.

Abstract: Provided are: a method for stabilizing an ascorbic acid oxidase; a method for preserving an ascorbic acid oxidase; and a stabilized composition of an ascorbic acid oxidase. A method for stabilizing an ascorbic acid oxidase and a method for preserving an ascorbic acid oxidase, each of the methods comprising allowing an ascorbic acid oxidase to coexist with nitrous acid or a salt thereof, or a nitrous acid ester in an aqueous medium; and a stabilized composition of an ascorbic acid oxidase, which comprises an ascorbic acid oxidase being allowed to coexist with nitrous acid or a salt thereof, or a nitrous acid ester in an aqueous medium. The method for stabilizing an ascorbic acid oxidase, the method for preserving an ascorbic acid oxidase, and the stabilized composition of an ascorbic acid oxidase according to the present invention are useful for clinical diagnosis and the like.

Abstract: Provided are: a method for stabilizing an ascorbic acid oxidase; a method for preserving an ascorbic acid oxidase; and a stabilized composition of an ascorbic acid oxidase. A method for stabilizing an ascorbic acid oxidase and a method for preserving an ascorbic acid oxidase, each of the methods comprising allowing an ascorbic acid oxidase to coexist with nitrous acid or a salt thereof, or a nitrous acid ester in an aqueous medium; and a stabilized composition of an ascorbic acid oxidase, which comprises an ascorbic acid oxidase being allowed to coexist with nitrous acid or a salt thereof, or a nitrous acid ester in an aqueous medium. The method for stabilizing an ascorbic acid oxidase, the method for preserving an ascorbic acid oxidase, and the stabilized composition of an ascorbic acid oxidase according to the present invention are useful for clinical diagnosis and the like.

Abstract: The present invention provides a method for stabilizing a cholesterol oxidase, a method for preserving a cholesterol oxidase, and a stabilized composition of cholesterol oxidase. A method for stabilizing a cholesterol oxidase and a method for preserving a cholesterol oxidase which comprises allowing the cholesterol oxidase to coexist with an ?-keto acid in an aqueous medium, and, a stabilized composition of cholesterol oxidase which comprises the cholesterol oxidase being allowed to coexist with an ?-keto acid in an aqueous medium. The method for stabilizing a cholesterol oxidase, the method for preserving a cholesterol oxidase, and a stabilized composition of cholesterol oxidase according to the present invention are useful for clinical diagnosis such as metabolic syndrome.

Abstract: Provided is a measuring method of a component to be measured in a specimen while suppressing an influence of bilirubin. A measuring method of a component to be measured, comprising converting the component to be measured in the specimen to hydrogen peroxide through an enzymatic reaction, reacting the formed hydrogen peroxide with an oxidative-coloring chromogen in the presence of a peroxidase, and measuring an absorbance of the colored reaction solution to thereby determine the component to be measured, wherein a fatty acid or a salt thereof coexists. The measuring method of a component to be measured in a specimen according to the present invention is useful in clinical diagnosis.

Abstract: A method for measuring cholesterol in low-density lipoprotein contained in a sample, which comprises reacting a sample with (i) a combination of cholesterol ester hydrolase and cholesterol oxidase or (ii) a combination of cholesterol ester hydrolase, an oxidized coenzyme and cholesterol dehydrogenase in the presence of: [a] a polyoxyethylene-polyoxyalkylene alkylaryl ether; [b] one or more surfactants selected from the group consisting of a polyoxyethylene-polyoxyalkylene copolymer, a polyoxyethylene alkenyl ether, a polyoxyethylene branched alkyl ether, and a polyoxyethylene-polyoxyalkylene branched alkyl ether; [c] one or more surfactants selected from the group consisting of a primary amine, a secondary amine, a tertiary amine, and a quaternary ammonium; and [d] a polyanion, and measuring a substance formed or consumed in the reaction.

Abstract: A method for determination of sdLDL-C in a reaction solution containing a surfactant that preferentially inhibits the reaction of sdLDL-C with enzymes for cholesterol measurement such as cholesterol ester hydrolase. In the method, the enzymes for cholesterol measurement act on a sample to eliminate HDL-C, VLDL-C, CM-C and LgLDL-C. A reagent that causes the reaction of sdLDL-C remaining in the reaction solution to form hydrogen peroxide or reduced coenzyme is then added, following which the formed hydrogen peroxide or reduced coenzyme is measured. The sdLDL-C concentration in the sample may be determined by comparing the measurement value with and a previously-prepared calibration curve.

Abstract: A method for measuring cholesterol in low-density lipoprotein contained in a sample, which comprises reacting a sample with (i) a combination of cholesterol ester hydrolase and cholesterol oxidase or (ii) a combination of cholesterol ester hydrolase, an oxidized coenzyme and cholesterol dehydrogenase in the presence of: [a] a polyoxyethylene-polyoxyalkylene alkylaryl ether; [b] one or more surfactants selected from the group consisting of a polyoxyethylene-polyoxyalkylene copolymer, a polyoxyethylene alkenyl ether, a polyoxyethylene branched alkyl ether, and a polyoxyethylene-polyoxyalkylene branched alkyl ether; [c] one or more surfactants selected from the group consisting of a primary amine, a secondary amine, a tertiary amine, and a quaternary ammonium; and [d] a polyanion, and measuring a substance formed or consumed in the reaction.

Abstract: A method for determination of sdLDL-C, which comprises the steps of: (i) in a reaction solution containing a surfactant which preferentially inhibits the reaction of sdLDL-C with enzymes for cholesterol measurement such as cholesterol ester hydrolase, allowing the enzymes for cholesterol measurement to act on a sample to eliminate HDL-C, VLDL-C, CM-C and LgLDL-C in the sample; (ii) adding a reagent which causes the reaction of sdLDL-C remaining in the reaction solution after the above step (i) to form hydrogen peroxide or reduced coenzyme, and measuring the formed hydrogen peroxide or reduced coenzyme; and (iii) determining the sdLDL-C concentration in the sample from the measurement value in (ii) and a previously prepared calibration curve.