Involvement of lactaldehyde dehydrogenase in several metabolic pathways of Escherichia coli K12.
Involvement of lactaldehyde dehydrogenase in several metabolic pathways of Escherichia coli K12.
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DOI：
10.1016/s0021-9258(18)47893-3
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发表时间：
1987-10
期刊：
影响因子：
--
通讯作者：
L. Baldomá;Juan AguilarS
中科院分区：
文献类型：
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作者：
L. Baldomá;Juan AguilarS
乳醛脱氢酶（E.C. 1.2.1.22）纯化至均一。它有四个明显相等的亚基（每个亚基的分子量为55，000），每个天然酶分子有四个NAD结合位点。这种酶只有在有氧条件下才能被至少三种不同类型的分子诱导，即岩藻糖和鼠李糖、二醇乙二醇和氨基酸谷氨酸。该酶催化几种醛的不可逆氧化，对于α-羟基醛（乳醛、甘油醛或乙醇醛），Km在微摩尔范围内，对于α-酮醛甲基乙二醛，Km在毫摩尔范围内。它对所有这些底物都显示出底物抑制作用。NAD是优先辅因子。该酶的功能和结构特征表明它不是其它大肠杆菌的同工酶。大肠杆菌醛脱氢酶如甘油醛磷酸脱氢酶、乙醇醛脱氢酶或乙醛脱氢酶。该酶，以前被描述为特定的乳醛，因此被确定为一种脱氢酶具有相当普遍的作用，醛氧化，它可能是参与几种代谢途径。
Lactaldehyde dehydrogenase (E.C. 1.2.1.22) of Escherichia coli has been purified to homogeneity. It has four apparently equal subunits (molecular weight 55,000 each) and four NAD binding sites per molecule of native enzyme. The enzyme is inducible, only under aerobic conditions, by at least three different types of molecules, the sugars fucose and rhamnose, the diol ethylene glycol and the amino acid glutamate. The enzyme catalyzes the irreversible oxidation of several aldehydes with a Km in the micromolar range for alpha-hydroxyaldehydes (lactaldehyde, glyceraldehyde, or glycolaldehyde) and a higher Km, in the millimolar range, for the alpha-ketoaldehyde methylglyoxal. It displays substrate inhibition with all these substrates. NAD is the preferential cofactor. The functional and structural features of the enzyme indicate that it is not an isozyme of other E. coli aldehyde dehydrogenases such as glyceraldehyde phosphate dehydrogenase, glycolaldehyde dehydrogenase, or acetaldehyde dehydrogenase. The enzyme, previously described as specific for lactaldehyde, is thus identified as a dehydrogenase with a fairly general role in aldehyde oxidation, and it is probably involved in several metabolic pathways.