Inhibition of plant acetyl-co a synthetase by alkyl-adenylates

Abstract

The plant acetyl-CoA synthetase (ACS) is bound to the plastids and provides acetyl-CoA, the starting substrate for de novo fatty acid biosynthesis in plastids. This enzymic reaction, which consumes ATP and releases A M P, can be inhibited by different alkyladenylates such as ethyl-, isopropyl-, propyl- or allyl-adenylates as is shown here. The inhibition mechanism is competitive with respect to ATP and non-com petitive with respect to acetate. I50-values and the inhibition constants Ki (ATP), Ki (acetate) and Kii (acetate) are given. The results suggest that, also in plants, acetyl-adenylate is the endogenous intermediate in the enzymic formation of acetyl-CoA from acetate by acetyl-CoA synthetase. © 1992, Walter de Gruyter. All rights reserved.