Some observations concerning enzymatic activity and lipid film on the human skin.

Abstract

Introduction Studies concerning the amount of free fatty acids in the lipids on the skin must of necessity concern themselves also with the activity of enzymes beneath and upon the skin surface. For the presence of free fatty acids on the skin surface presumably is to a great extent due to lipolysis, i. e., to the hydrolytic breakdown of esters, produced by different esterases. Biochemical and histochemical analysis has shown that such enzymes are present physiologically in the skin. 1-3 In addition, however, lipolytic enzymes are produced in great measure by the microbial flora on the skin. Besides the enzymatic liberation of fatty acids outside and inside the skin, enzymatic esterification occurs in the skin as well. Kooyman, for example, demonstrated esterification of cholesterol in the epidermal cells. 4 Nicolaides and Rothman, moreover, demonstrated that human skin is able to synthesize fatty acids in vitro (from