Shimakata T, Stumpf P K
Arch Biochem Biophys. 1983 Jan;220(1):39-45. doi: 10.1016/0003-9861(83)90384-3.
beta-Ketoacyl-acyl carrier protein (ACP) synthetase I was purified 180-fold from crude extracts of spinach leaves. The purified preparation was completely free from other component enzymes of the de novo fatty acid synthetase (FAS) system. Its molecular weight was estimated to be 56,000 by gel filtration. The apparent Km value for malonyl-CoA in the presence of ACP and malonyl-CoA:ACP transacylase was 4 microM. Purified synthetase I was highly active with acyl-ACP having chain lengths from C2 to C14, with hexanoyl-ACP being the most effective substrate, but palmitoyl-ACP was far less effective and stearoyl-ACP almost inactive. The antibiotic, cerulenin, strongly inhibited synthetase I activity. The inhibition by cerulenin was protected by prior incubation with hexanoyl-ACP, decanoyl-ACP, and myristoyl-ACP. The synthetase was inhibited by 1 mM p-CMB and 5 mM NEM, but not by 1 mM arsenite.
β-酮脂酰-酰基载体蛋白（ACP）合成酶I从菠菜叶粗提物中纯化了180倍。纯化后的制剂完全不含从头脂肪酸合成酶（FAS）系统的其他组成酶。通过凝胶过滤法估计其分子量为56,000。在存在ACP和丙二酰-CoA：ACP转酰基酶的情况下，丙二酰-CoA的表观Km值为4 microM。纯化的合成酶I对链长从C2到C14的酰基-ACP具有高活性，其中己酰-ACP是最有效的底物，但棕榈酰-ACP的效果要差得多，硬脂酰-ACP几乎无活性。抗生素浅蓝菌素强烈抑制合成酶I的活性。预先用己酰-ACP、癸酰-ACP和肉豆蔻酰-ACP孵育可保护浅蓝菌素的抑制作用。该合成酶被1 mM对氯汞苯甲酸（p-CMB）和5 mM N-乙基马来酰亚胺（NEM）抑制，但不被1 mM亚砷酸盐抑制。
