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    請使用永久網址來引用或連結此文件: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/61695

    題名: Protein-coenzyme Interactions in adenosylcobalamin-dependent glutamate mutase
    作者: Huhta, M.S.;Chen, H.P.;Hemann, C.;Hille, C.R.;Marsh, E.N.
    貢獻者: 淡江大學化學學系
    關鍵詞: Enzyme;Resonance Raman spectroscopy;Vitamin B 12
    日期: 2001-07
    上傳時間: 2013-05-31 11:34:29 (UTC+8)
    出版者: London: Portland Press
    摘要: Glutamate mutase catalyses an unusual isomerization involving free-radical intermediates that are generated by homolysis of the cobalt-carbon bond of the coenzyme adenosylcobalamin (coenzyme B(12)). A variety of techniques have been used to examine the interaction between the protein and adenosylcobalamin, and between the protein and the products of coenzyme homolysis, cob(II)alamin and 5'-deoxyadenosine. These include equilibrium gel filtration, isothermal titration calorimetry, and resonance Raman, UV-visible and EPR spectroscopies. The thermodynamics of adenosylcobalamin binding to the protein have been examined and appear to be entirely entropy-driven, with DeltaS=109 J.mol(-1).K(-1). The cobalt-carbon bond stretching frequency is unchanged upon coenzyme binding to the protein, arguing against a ground-state destabilization of the cobalt-carbon bond of adenosylcobalamin by the protein. However, reconstitution of the enzyme with cob(II)alamin and 5'-deoxyadenosine, the two stable intermediates formed subsequent to homolysis, results in the blue-shifting of two of the bands comprising the UV-visible spectrum of the corrin ring. The most plausible interpretation of this result is that an interaction between the protein, 5'-deoxyadenosine and cob(II)alamin introduces a distortion into the ring corrin that perturbs its electronic properties.
    關聯: Biochemical Journal 355(1), pp.131-137
    DOI: 10.1042/0264-6021:3550131
    顯示於類別:[化學學系暨研究所] 期刊論文





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