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Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
Published on: November 23, 2016
Ethanolamine ammonia-lyase has a "base-on" binding mode for coenzyme B(12)
A Abend1, V Bandarian, R Nitsche
1Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, 53705, USA.
Abstract:
Ethanolamine ammonia-lyase (EAL, EC 4.3.1.7) catalyzes a coenzyme B(12)-dependent deamination of vicinal amino alcohols. The mode of binding of coenzyme B(12) to EAL has been investigated by electron paramagnetic resonance spectroscopy (EPR) using [(15)N]-dimethylbenzimidazole-coenzyme B(12). EAL was incubated with either unlabeled or (15)N-enriched coenzyme B(12) and then either exposed to light or treated with ethanol to generate the cleaved form of the cofactor, cob(II)alamin (B(12r)) bound in the active site. The reaction mixtures were examined by EPR spectroscopy at 77 K. (15)N superhyperfine splitting in the EPR signals of the low-spin Co(2+) of B(12r), bound in the active site of EAL, indicates that the dimethylbenzimidazole moiety of the cofactor contributes the lower axial ligand consistent with "base-on" binding of coenzyme B(12) to EAL.
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