Fatty acid synthetases from Euglena gracilis

Abstract

Fatty acid synthetases catalyzing the TPNH-dependent incorporation of acetyl-CoA and malonyl-CoA into long-chain fatty acids have been isolated from both etiolated and green cells of Euglena gracilis , strain Z. Conditions for growing the phytoflagellate determine the type of enzyme activity. Synthetase isolated from dark-grown Euglena is a complex of high molecular weight that produces in the main palmitate and shorter-chain acids and does so in the absence of added acyl carrier protein. By contrast, cells grown in the light on a mineral medium yield two distinct and separable fatty acid synthetases. One has the same properties as the synthetase found in the dark-grown cells. The second enzyme system present in extracts of green Euglena depends for activity on added acyl carrier protein and appears to be composed of individual, nonaggregating enzymes. Stearate and longer-chain acids are the main products of this second system.