Biochemical and molecular characterization of α-ketoisovalerate decarboxylase, an enzyme involved in the formation of aldehydes from amino acids by Lactococcus lactis
Biochemical and molecular characterization of α-ketoisovalerate decarboxylase, an enzyme involved in the formation of aldehydes from amino acids by Lactococcus lactis
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DOI：
10.1111/j.1574-6968.2004.tb09778.x
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发表时间：
2004-09-15
影响因子：
2.1
通讯作者：
Requena, T
中科院分区：
文献类型：
--
作者：
de la Plaza, M;de Palencia, PF;Requena, T
在本文中，我们首次报告的α-酮异戊酸脱羧酶的鉴定，纯化和表征的乳酸乳球菌，一种新的酶，负责脱羧成醛的α-酮酸来自氨基酸转氨。kivd基因由一个1647 bp的开放阅读框组成，编码一个61 kDa的多肽。推导的氨基酸序列的分析表明，该酶是一种非氧化性硫胺素二磷酸（ThDP）依赖性α-酮酸脱羧酶包括在丙酮酸脱羧酶组的酶。活性酶是一种同源四聚体，在45 degreesC和pH 6.5时显示出最佳活性，并表现出典型的金属依赖性酶的抑制模式。除Mg 2+外，在其它二价阳离子如Ca 2+、Co 2+和Mn 2+存在下观察到活性。该酶对α-酮异戊酸（缬氨酸和亮氨酸生物合成的中间代谢物）表现出最高的比活性（80.7 U mg（-1））。另一方面，吲哚-3-丙酮酸和丙酮酸的脱羧仅可通过反应中存在的酶浓度增加100倍来检测。(C)2004年，欧洲微生物学会联合会。Elsevier B. V.出版，保留所有权利。
In this paper, we report for the first time on the identification, purification, and characterization of the alpha-ketoisovalerate decarboxylase from Lactococcus lactis, a novel enzyme responsible for the decarboxylation into aldehydes of alpha-keto acids derived from amino acid transamination. The kivd gene consisted of a 1647 bp open reading frame encoding a putative peptide of 61 kDa. Analysis of the deduced amino acid sequence indicated that the enzyme is a non-oxidative thiamin diphosphate (ThDP)-dependent alpha-keto acid decarboxylase included in the pyruvate decarboxylase group of enzymes. The active enzyme is a homo-tetramer that showed optimum activity at 45 degreesC and at pH 6.5 and exhibited an inhibition pattern typical for metal-dependant enzymes. In addition to Mg2+, activity was observed in presence of other divalent cations such as Ca2+, Co2+ and Mn2+. The enzyme showed the highest specific activity (80.7 U mg(-1)) for alpha-ketoisovalerate, an intermediate metabolite in valine and leucine biosynthesis. On the other side, decarboxylation of indole-3-pyruvate and pyruvate only could be detected by a 100-fold increase in the enzyme concentration present in the reaction. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.