Identification of a paramagnetic species as an early intermediate in the coenzyme B12‐dependent glutamate mutase reaction A cob(II)amide?

FEBS Letters

Leutbecher, U.²  Albracht, S.P.J.¹  Buckel, W.² 

[1] E.C. Slater Institute for Biochemical Research, NL-1018 TV Amsterdam, The Netherlands;Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps—Universität, W-3550 Marburg, Germany

关键词: Adenosylcobalamin;    Coenzyme B12;    Glutamate mutase;    Clostridium cochlearium;    Electron paramagnetic resonance;   

DOI  :  10.1016/0014-5793(92)80754-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Highly active and cobamide-free glutamate mutase was obtained from Clostridium cochlearium by a modification of the original purification procedure. After incubation of the enzyme with dithiothreitol, adenosylcobalamin (coenzyme B₁₂) and the substrate (S)-glutamate, a paramagnetic species was observed by EPR-spectroscopy. The signal was maximal within 15 ms after mixing with glutamate. Different signals were detected after incubating the system with the competitive inhibitors (2S,4S)-4-fluoroglutamate or 2-methyleneglutarate instead of the substrate. The former developed with an at least 100-fold lower rate then the signal with glutamate. All three signals are probably due to low-spin cob(II)amide species with an extraordinary low g_xy value as compared with cob(II)alamin.

【 授权许可】

Unknown