The enzymatic formation of novel bile acid primary amides.
The enzymatic formation of novel bile acid primary amides.
复制标题
新型胆汁酸伯酰胺的酶促形成。
DOI：
10.1006/abbi.1999.1611
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Merkler,DJ
中科院分区：
文献类型：
--
作者：
King3rd,L;Barnes,S;Glufke,U;Henz,ME;Kirk,M;Merkler,KA;Vederas,JC;Wilcox,BJ;Merkler,DJ
双功能肽基甘氨酸α-酰胺化单加氧酶（PAM）可催化c端甘氨酸延伸肽和n -酰基甘氨酸的铜、抗坏血酸和o2依赖性裂解，生成相应的酰胺和乙醛酸盐。α-酰胺肽和长链丙烯酰胺是人类和其他哺乳动物的激素。胆汁酸甘氨酸缀合物也是PAM的底物，导致胆汁酸酰胺的形成。胆汁酸甘氨酸缀合物的（VMAX/Km）值与其他已知的PAM底物相当。3-亚基基酰甘氨酸的VMAX/Km值最高，为3.1±0.12 × 105M−1s−1，比代表性肽底物d-Tyr-Val-Gly高6.7倍。o2消耗和乙醛酸酯生成的时间过程表明，胆汁酸-甘氨酸共轭酰胺化是一个两步反应。胆汁酸甘氨酸缀合物首先转化为n -胆酰-α-羟基甘氨酸中间体，该中间体最终脱烷基生成胆汁酸酰胺和乙醛酸酯。采用质谱法和二维h - 13c异核多重量子相干核磁共振对酶法合成的胆汁酸酰胺和碳酰胺中间体进行了表征。
Bifunctional peptidylglycine α-amidating monooxygenase (PAM) catalyzes the copper-, ascorbate-, and O2-dependent cleavage of C-terminal glycine-extended peptides and N-acylglycines to the corresponding amides and glyoxylate. The α-amidated peptides and the long-chain acylamides are hormones in humans and other mammals. Bile acid glycine conjugates are also substrates for PAM leading to the formation of bile acid amides. The (VMAX/Km)appvalues for the bile acid glycine conjugates are comparable to other known PAM substrates. The highest (VMAX/Km)appvalue, 3.1 ± 0.12 × 105M−1s−1for 3-sulfolithocholylglycine, is 6.7-fold higher than that for d-Tyr–Val–Gly, a representative peptide substrate. The time course for O2consumption and glyoxylate production indicates that bile acid glycine conjugate amidation is a two-step reaction. The bile acid glycine conjugate is first converted to an N-bile acyl-α-hydroxyglycine intermediate which is ultimately dealkylated to the bile acid amide and glyoxylate. The enzymatically produced bile acid amides and the carbinolamide intermediates were characterized by mass spectrometry and two-dimensional1H–13C heteronuclear multiple quantum coherence NMR.