Acyl-CoA Synthetase in Maturing Safflower Seeds

概要

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Acyl-CoA synthetase in maturing seeds of safflower (Carthamus tinctorius) was membrane-bound, and the highest specific activity was associated with microsomes. Activity absolutely depended on the concentrations of fatty acid, CoA, ATP and Mg^<2+> . The apparent K_m values were 4.2 μM for oleate, 24 μM for CoA, and 250 μM for ATP. The optimum pH of the reaction was 7.5. Triacsin C, a potent inhibitor of the animal and bacterial acyl-CoA synthetase, was ineffective for the safflower enzyme. The enzyme utilized C_<16 >and C_<18> long-chain fatty acids preferentially, while medium-chain and very-long-chain fatty acids were poor substrates. The order of specificity for native fatty acids was linoleate>oleate=palmitate>stearate. Although activity per seed varied during seed maturation, it was enough to account for the rate of triacylglycerol synthesis in vivo.
日本植物生理学会の論文