Steryl glycoside acyltransferase from carrots

Abstract

Acylated steryl glycoside (ASG) of higher plants [l-4,8] is synthesized in two steps: a) glycosylation of a sterol and b) subsequent acylation of the steryl glycoside (SG) [5,6]. Enzymes catalyzing the two reactions in vitro have been found in seeds, seedlings and storage tissue‘of different plants [2,5,7]. The formation of ASG is worth investigating, because the acyl transfer is closely related to the lipid metabolism of the cell. In most cases, the enzyme activity was found to be associated with microsomal structures. A soluble enzyme was obtained in the high-speed supernatant from carrots [7] homogenized with water. A similar activity was found in wheat seedlings homogenized with 0.5% Triton X-100 [6]. The present work reports on the purification and characterization of the acyltransferase from carrots, which we call steryl glycoside acyltransferase (SGAT).