Bierbach H
Gut. 1980 Aug;21(8):689-94. doi: 10.1136/gut.21.8.689.
Long chain fatty acid:CoA ligase (EC 6.2.1.3.) was examined in human small intestinal mucosa using the hydroxamate-trapping method. With optimal assay requirements using palmitate as substrate a significant difference of specific activities could be detected in the total homogenate from duodenum, 40.9 +/- 11.6 nmol/min per mg protein versus upper jejunum, 51.9 +/- 13.7 (P less than 0.05). The enzyme activity of the microsomal fraction of upper jejunum was 101.8 +/- 44 nmol/min per mg protein. ATP, CoA, and Mg2+ were essential constituents of the reaction. A broad pH-optimum was observed between 6.75 and 7.75 with a maximum at a pH of 7.25. Whereas palmitate in the presence of albumin revealed a wide range of optimal concentration in supporting maximal enzyme activity, oleate was found to strongly inhibit the reaction. Where substrate specificity with both the total homogenate and the microsomal fraction was concerned, maximal reaction rates were obtained with palmitate for the long chain saturated fatty acids C12:0' C14:0' C16:0' and C18:0' and with oleate for the long chain unsaturated fatty acids C18:1 C18:2' and C18:3' respectively. The highest specific activity of the enzyme was localised in the microsomal fraction. The kinetic data and properties of the long chain fatty acid: CoA ligase from human intestine are discussed with respect to the intestinal enzyme from other species.
采用异羟肟酸捕获法对人小肠黏膜中的长链脂肪酸辅酶A连接酶（EC 6.2.1.3.）进行了检测。以棕榈酸为底物，按照最佳检测条件，在十二指肠总匀浆中检测到的比活性为40.9±11.6 nmol/（min·mg蛋白），而在上段空肠中为51.9±13.7（P<0.05），二者存在显著差异。上段空肠微粒体部分的酶活性为101.8±44 nmol/（min·mg蛋白）。ATP、辅酶A和Mg2+是该反应的必需成分。观察到在pH 6.75至7.75之间有较宽的最适pH范围，在pH 7.25时达到最大值。在白蛋白存在的情况下，棕榈酸在支持最大酶活性方面显示出较宽的最佳浓度范围，而油酸则被发现强烈抑制该反应。就总匀浆和微粒体部分的底物特异性而言，对于长链饱和脂肪酸C12:0、C14:0、C16:0和C18:0，棕榈酸可获得最大反应速率，对于长链不饱和脂肪酸C18:1、C18:2和C18:3，油酸可分别获得最大反应速率。该酶的最高比活性位于微粒体部分。本文还结合其他物种的肠道酶，对人肠道长链脂肪酸辅酶A连接酶的动力学数据和特性进行了讨论。
