T. Jacks, H. W. Kircher
Nov 1, 1967
Citations
4
Influential Citations
151
Citations
Quality indicators
Journal
Analytical biochemistry
Abstract
Abstract Butyryl, hexanoyl, heptanoyl, nonanoyl, palmitoyl, and oleoyl esters of 4-methylumbelliferone were synthesized and tested as substrates to determine the hydrolytic activity of five preparations of acid or alkaline lipases. The highest rate of hydrolysis was obtained with the hexanoyl ester for steapsin, the heptanoyl ester for wheat germ and peanut lipases, the octanoyl ester for castor bean lipase, and the nonanoyl ester for porcine lipase; relative variations in the rates with the other esters were found among the enzymes. Enzymic hydrolysis of these nonfluorescent esters releases intensely fluorescent 4-methylumbelliferone; the course of the hydrolytic reaction is continuously observed by spectrofluorometric measurement of the rate of the production of fluorescence. By this procedure the apparent Michaelis constant (Km) for the catalysis of heptanoyl 4-methylumbelliferone by the lipase preparations and the specific activities of the preparations were determined and are reported.