Non-covalent modification of the heme-pocket of apomyoglobin by a 1,10-phenanthroline derivative |
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Authors: | Hitomi Yutaka Mukai Hidefumi Yoshimura Hideaki Tanaka Tsunehiro Funabiki Takuzo |
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Affiliation: | Department of Molecular Engineering, Kyoto University, Kyoto Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan. hitomi@moleng.kyoto-u.ac.jp |
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Abstract: | To expand the repertoire of artificial enzymes that are constructed by replacing the natural prosthetic group of hemoproteins with non-natural cofactors, we examined incorporation of a non-porphyrinic ligand (1) into the heme-pocket of apomyoglobin in a non-covalent fashion. Ligand 1 is a highly conjugated 1,10-phenanthroline derivative, which shares some structural features with protoporphyrin IX; for example, molecular size and arrangement of hydrophobic and anionic parts. Addition of apomyoglobin to a solution of 1 induces clear changes in the absorption spectrum of 1, suggesting one-to-one incorporation of 1 into the heme cavity of apomyoglobin with an affinity of 6.3 x 10(6)M(-1). We found that the hydrolytic activity of apomyoglobin toward p-nitrophenyl hexanoate was greatly suppressed because of the incorporation of 1 into the heme-pocket. |
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