N-substituted formamide was produced through the hydration of an isonitrile by isonitrile hydratase in the isonitrile metabolism. The former compound was further degraded by a microorganism, strain F164, which was isolated from soil through an acclimatization culture. The N-substituted formamide-degrading microorganism was identified as
Arthrobacter pascens
. The microbial degradation was found to proceed through an enzymatic reaction, the N-substituted formamide being hydrolyzed to yield the corresponding amine and formate. The enzyme, designated as N-substituted formamide deformylase (NfdA), was purified and characterized. The native enzyme had a molecular mass of ≈61 kDa and consisted of two identical subunits. It stoichiometrically catalyzed the hydrolysis of
N
-benzylformamide (an N-substituted formamide) to benzylamine and formate. Of all of the N-substituted formamides tested,
N
-benzylformamide was the most suitable substrate for the enzyme. However, no amides were accepted as substrates. The gene (
nfdA
) encoding this enzyme was also cloned. The deduced amino acid sequence of
nfdA
exhibited the highest overall sequence identity (28%) with those of regulatory proteins among known proteins. Only the N-terminal region (residues 58–72) of NfdA also showed significant sequence identity (27–73%) to that of each member of the amidohydrolase superfamily, although there was no similarity in the overall sequence except in the above limited region.
在异腈代谢中,异腈水合酶通过异腈的水合反应产生了N-取代甲酰胺。微生物菌株F164通过驯化培养从土壤中分离出来,进一步降解了前者化合物。N-取代甲酰胺降解微生物被鉴定为Arthrobacter pascens。发现微生物降解是通过一种酶促反应进行的,即N-取代甲酰胺水解生成相应的胺和甲酸。该酶被命名为N-取代甲酰胺脱甲基酶(NfdA),并进行了纯化和表征。天然酶的分子质量约为61 kDa,由两个相同的亚基组成。它可以催化N-苄基甲酰胺(一种N-取代甲酰胺)的水解,生成苄胺和甲酸。在所有测试的N-取代甲酰胺中,N-苄基甲酰胺是该酶最适合的底物。但是,该酶不接受酰胺作为底物。该酶的编码基因(nfdA)也被克隆。推导出的nfdA氨基酸序列在已知蛋白质中与调节蛋白质的总体序列同源性最高(28%)。除了上述有限区域外,NfdA的整体序列没有相似性,但其N端区域(残基58-72)也显示出与酰胺水解酶超家族的每个成员的序列同源性(27-73%)。