Malcorps P, Dufour J P
Unité de Brasserie et des Industries Alimentaires, Université Catholique de Louvain, Belgium.
Eur J Biochem. 1992 Dec 15;210(3):1015-22. doi: 10.1111/j.1432-1033.1992.tb17507.x.
In the yeast Saccharomyces cerevisiae, the enzymes which catalyse the synthesis of ethyl acetate, ethyl n-hexanoate and isoamyl acetate were partly resolved from a fraction containing slowly sedimenting lipoproteins released during cell disruption with glass beads. Solubilization with detergents and fractionation by affinity chromatography have demonstrated the presence of at least three, and probably four, ester synthases which differ in their catalytic properties. Isoamyl-acetate synthase was solubilized and extensively purified to apparent homogeneity by successive chromatographies on various columns. On the basis of its specific activity in cell-free extracts, the enzyme was purified 19,000-fold with a 5% activity yield. As judged by SDS/PAGE, it consists of a single polypeptide chain with a molecular mass of 57 +/- 3 kDa and its apparent pI is 5.5. The enzyme acetylates isoamyl alcohol, ethanol and 12-DL-hydroxystearic acid from acetyl-CoA but is unable to use n-hexanoyl-CoA as a cosubstrate. This enzyme, defined as an acetyl-CoA: O-alcohol acetyltransferase, could be the product of one of the anaerobically induced genes in S. cerevisiae.
在酿酒酵母中，催化乙酸乙酯、正己酸乙酯和乙酸异戊酯合成的酶，部分是从含有在玻璃珠破碎细胞过程中释放出的缓慢沉降脂蛋白的组分中分离得到的。用去污剂增溶并通过亲和层析分级分离，已证明存在至少三种，可能四种催化特性不同的酯合成酶。乙酸异戊酯合成酶通过在各种柱上连续层析被增溶并广泛纯化至表观均一性。根据其在无细胞提取物中的比活性，该酶纯化了19,000倍，活性回收率为5%。通过SDS/PAGE判断，它由一条分子量为57±3 kDa的单多肽链组成，其表观pI为5.5。该酶从乙酰辅酶A乙酰化异戊醇、乙醇和12-DL-羟基硬脂酸，但不能使用正己酰辅酶A作为共底物。这种被定义为乙酰辅酶A：O-醇乙酰转移酶的酶，可能是酿酒酵母中厌氧诱导基因之一的产物。
