Reaction of the Co(II)-substrate radical pair catalytic intermediate in coenzyme B12-dependent ethanolamine ammonia-lyase in frozen aqueous solution from 190 to 217 K.

ABSTRACT: The decay kinetics of the aminoethanol-generated Co(II)-substrate radical pair catalytic intermediate in ethanolamine ammonia-lyase from Salmonella typhimurium have been measured on timescales of <10(5) s in frozen aqueous solution from 190 to 217 K. X-band continuous-wave electron paramagnetic resonance (EPR) spectroscopy of the disordered samples has been used to continuously monitor the full radical pair EPR spectrum during progress of the decay after temperature step reaction initiation. The decay to a diamagnetic state is complete and no paramagnetic intermediate states are detected. The decay exhibits three kinetic regimes in the measured temperature range, as follows. i), Low temperature range, 190 < or = T < or = 207 K: the decay is biexponential with constant fast (0.57 +/- 0.04)

SUBMITTER: Zhu C 

PROVIDER: S-EPMC2599855 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature