RAPID ENZYMATIC DETERMINATION OF FREE AND ESTERIFIED CHOLESTEROL CONTENT OF SERUM AND TISSUES

An enzymatic method for determination of total serum cholesterol utilizes hydrolysis of the esters by the enzyme cholesterol ester hydrolase, followed by conversion of cholesterol to cholest-4-en-3-one and H2O2 by a cholesterol oxidase. The H2O2 is quantitated by oxidative coupling of 4-aminoantipyrine and phenol to form a colored product whose absorbance can be measured at 500 nm. This method has equal or greater accuracy and greater specificity than the standard colorimetric methods. This study evaluated the possible adaptation of this enzymatic method to determine both free and esterified cholesterol concentrations in serum and tissues. Results indicate that an enzymatic method, utilizing a single aqueous reagent, can be employed for rapid and accurate determination of both free and esterified cholesterol content of serum and tissue. Specificity for cholesterol is higher with the enzymatic method than with the colorimetric methods, and the former is not subject to interference by hemolysis, lipemia or steroid drugs.