Biohydrogenation of Unsaturated Fatty Acids IV. SUBSTRATE SPECIFICITY AND INHIBITION OF LINOLEATE Δ12-CIS, Δ11-TRANS-ISOMERASE FROM BUTYRIVIBRIO FIBRISOLVENS
Biohydrogenation of Unsaturated Fatty Acids IV. SUBSTRATE SPECIFICITY AND INHIBITION OF LINOLEATE Δ12-CIS, Δ11-TRANS-ISOMERASE FROM BUTYRIVIBRIO FIBRISOLVENS
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发表时间：
1970-07
影响因子：
4.8
通讯作者：
C. R. Kepler;W. P. Tucker;S. B. Tove
中科院分区：
文献类型：
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作者：
C. R. Kepler;W. P. Tucker;S. B. Tove
摘要通过脂肪酸异构体和类似物的抑制研究，确定了底物与溶纤维丁酸弧菌亚油酸异构酶结合的三个参数。它们是(a)底物双键的π体系，(b)疏水相互作用，(c)底物羧基的氢键。几乎所有被测试的不饱和脂肪酸都能抑制这种酶，无论碳3和碳12之间的构型或双键位置如何。在不饱和的贡献上叠加的是抑制作用与链长和C-1取代基上活性氢的存在的相关性。不饱和脂肪酸或其衍生物的抑制作用在所有情况下都是竞争性的。通过与底物的位置和构型异构体和羧基衍生物孵育，揭示了对异构化的更严格要求。必须有顺式9、顺式12二烯体系和游离的C-1羧基。两种螯合剂，邻菲罗啉和EDTA，被确定为酶的可逆抑制剂。邻菲罗啉的抑制是非竞争性的。巯基试剂、对羟基汞苯甲酸酯、碘乙酰胺和n -乙基马来酰亚胺对异构酶也有抑制作用。
Abstract Three parameters involved in the binding of substrate to linoleate isomerase of Butyrivibrio fibrisolvens have been identified from studies of inhibition by fatty acid isomers and analogues. They are (a) the π system of the substrate double bond, (b) hydrophobic interaction, and (c) hydrogen bonding of the substrate carboxyl group. Almost every unsaturated fatty acid tested inhibited the enzyme, regardless of configuration or double bond position between carbons 3 and 12. Superimposed on this contribution of unsaturation was the correlation of inhibition with chain length and with the presence of an active hydrogen on a C-1 substituent. Inhibition by unsaturated fatty acids or their derivatives in all cases examined was competitive. More restrictive requirements for isomerization were revealed by incubation of the enzyme with positional and configurational isomers and carboxyl derivatives of the substrate. An absolute requirement for a cis-9, cis-12-diene system and a free C-1 carboxyl group was shown. Two chelators, o-phenanthroline and EDTA, were identified as reversible inhibitors of the enzyme. Inhibition by o-phenanthroline was noncompetitive. The isomerase was also inhibited by the sulfhydryl reagents, p-hydroxymercuribenzoate, iodoacetamide, and N-ethylmaleimide.