THE SIMPLE ESTERASES OF HUMAN SKIN.

THE simple skin esterases discussed liere are those that act on esters of short chain fatty acids. They differ from the lipases, which act on esters of long chain fatty acids and behave otherwise towards activators and inhibitors. Agnes Porter (1916) first demonstrated that human skin could hydrolyse tribntyi'in. tlie ester of a short chained fatty acid, by enzyme action. The features of this activity were further studied by otJiers, altliougli their methods were somewhat insensitive and the results not always conclusive by later standards (Sexsinith and Petersen. If*IS ; Wohlgemuth and Nakamura, l\)-2ii ; Melczer, 11)27). Thompson anti Whittaker (1944) Initiated several recent studies on akin esterases which have been reviewed and extended by Magnus and Thompson (!9.")4). Skin choHnesterases were found to be |)eculiar in acting very .slightly on esters of short chain fattj' acids. Hydrolysi.s of these esters was shown to l>e attributable almost entirely to an enzyme other than cholinesterase, and jjerhaps to a plurality of enzymes. In testing simple esterase activity the more commonly selected alcoholic moieties in the ester may conveniently be substituted by liaphthol. One may then use the liberated naphthol as a sensitive measure of hydrolysis both biochemically and histoehemically by means of azo coupling. Nachlas and Seliginan (1049a) introdticed these naphtholic substrates, and Gomori (U'ii-*) has applied and simplified the methods. In the present study, Gomori's techniques essentially were used.