Hydrogen bonding of flavoprotein: II. Effect of hydrogen bonding at hetero atoms of reduced flavin on its reactivity |
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Authors: | Kichisuke Nishimoto Eiko Kai Kunio Yagi |
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Institution: | 1. Department of Chemistry, Faculty of Science, Osaka City University, Osaka 558, Japan;2. Institute of Applied Biochemistry, Yagi Memorial Park, Mitake, Gifu 505-01, Japan |
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Abstract: | The effect of hydrogen bonding at hetero atoms of reduced flavin on its reactivity was studied by ab initio molecular orbital calculations. Among the atoms in the isoalloxazine nucleus of lumiflavin, C(4a) was found to be the most reactive with neutral electrophiles such as molecular oxygen, whereas no reactivity of N(5) can be expected, because of its negative charge. The reactivity of C(4a) is markedly enhanced by hydrogen bonding at N(1) and N(3) in a hydrophobic environment, while it is decreased when hydrogen bonding occurs at all the hetero atoms, as in the case of an aqueous solution of flavin. |
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Keywords: | Hydrogen bonding Flavin reactivity Flavoprotein |
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