CHARACTERIZATION OF FATTY-ACID ELONGASE ENZYMES FROM GERMINATING PEA-SEEDS

In vitro biosynthesis of radioactive arachidate and behenate was obser ved when microsomal fractions of germinating pea seeds were incubated with exogenous stearoyl-CoA (18:0-CoA) or arachidoyl-CA (20:0-CoA) in the presence of NADPH, [2-C-14]malonyl-CoA and ATP. Characterization o f parameters required for optimal stearoyl- and arachidoyl-CoA elongat ion revealed that, at least, two chain-length-specific elongases are n ecessary for very-long-chain fatty acid synthesis. Both enzymes were f ound to be sensitive to the group selective reagents, p-CMB, NEM, iodo acetate, arsenite and phenylglyoxal. Subcellular fractionation studies indicated that both of these elongases were localized mainly in the e ndoplasmic reticulum. (C) 1998 Elsevier Science Ltd. All rights reserv ed.