Manometric assay and properties of pancreatic cholesterol esterase.

It has long been known that enzymically catalysed synthesis and hydrolysis of cholesterol esters occurs in the presence of certain tissues (Kondo, 1910a, b; Schultz, 1912; Cytronberg, 1912; Gardner & Lander, 1913; Mueller, 1916a, b; Porter, 1916; Nomura, 1924a, b; Shope, 1928; Nedswedski, 1935, 1936; Klein, 1939; Sperry, 1935; Sperry & Stoyanoff, 1937, 1938). The most extensive recent studies, initiated with the enzyme from pancreas, are those of Yamamoto, Goldstein & Treadwell (1949) and Swell & Treadwell (1950a), who stressed the importance of stable emulsions of cholesterol and cholesterol esters and described their preparation. By use of these mixtures numerous properties of the cholesterol esterase present in serum (Swell & Treadwell, 1950b) and in homogenates of various organs were studied (Swell, Byron & Treadwell, 1950; Byron, Wood & Treadwell, 1953; Swell, Dailey, Field & Treadwell, 1955). Hydrolysis of cholesteryl acetate catalysed by an enzyme present in the microsomal fraction of rat liver has been observed by Schotz, Rice & Alfin-Slater (1954). Some properties of purified pancreatic cholesterol esterase have been reported by Hernandez & Chaikoff (1957), who devised a rapid turbidimetric method for estimation of enzymic activity. The present report describes some characteristics of the cholesterol esterase, which is found in extracts of acetone-dried pancreas, and defines the conditions required to demonstrate high catalytic activity. The data were obtained by use of a manometric procedure for estimation of synthesis or hydrolysis of cholesterol esters. Brief reports of some of the data have been made (Korzenovsky, Rust & Diller, 1955; Korzenovsky, Vesely & Diller, 1956).