Photolysis of adenosylcobalamin and radical pair recombination in ethanolamine ammonia-lyase probed on the micro- to millisecond time scale by using time-resolved optical absorption spectroscopy.
作者： Wesley D. Robertson , Kurt Warncke
DOI: 10.1021/BI801659E
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摘要: The quantum yield and kinetics of decay cob(II)alamin formed by pulsed-laser photolysis adenosylcobalamin (AdoCbl; coenzyme B12) in AdoCbl-dependent ethanolamine ammonia-lyase (EAL) from Salmonella typhimurium have been studied on the 10−7−10−1 s time scale at 295 K using transient ultraviolet−visible absorption spectroscopy. aim is to probe mechanism formation stabilization cob(II)alamin−5′-deoxyadenosyl radical pair, which a key intermediate EAL catalysis, influence substrate binding this process. Substrate required for cobalt−carbon bond cleavage native system. Photolysis AdoCbl leads 10−7 0.08 ± 0.01, 3-fold smaller than aqueous solution (0.23 0.01). protein site therefore suppresses photoproduct pair formation. Three states, Pf, Ps, Pc, are identified holo-EAL different (subscrip...
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