The role of His117 in the redox reactions of azurin from Pseudomonas aeruginosa

FEBS Letters

Gorren, Antonius C.F.³  Hopper, David J.²  Canters, Gerard W.¹  Duine, Johannis A.³  den Blaauwen, Tanneke¹ 

[1] Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands;Institute of Biological Sciences, University of Wales, Aberystwyth, Dyfed SY23 3DD Wales, UK;Department of Microbiology and Enzymology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands

关键词: Azurin;    Histidine 117;    Imidazole;    4-Ethylphenol methylene hydroxylase;    Redox reaction;    4-EPMH;    4-ethylphenol methylenehydroxylase;    Im;    imidazole;    1-MeIm;    1-methylimidazole;    2-MeIm;    2-methylimidazole;    4-MeIm;    4-methylimidazole;    2-AmIm;    2-aminoimidazole;    4-NiIm;    4-nitroimidazole;    1-MeIm;    1-Methylimidazole;    2-Mc-1-MeIm;    2-mercapto-1-methylimidazole;   

DOI  :  10.1016/0014-5793(96)00076-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The electron-transfer properties of H117G- and wild-type azurin were compared by applying both as electron acceptors in the conversion of 4-ethylphenol by 4-ethylphenol methylenehydroxylase (4-EPMH). The reactivity of H117G-azurin was determined in the absence and presence of imidazoles, which can substitute the missing fourth ligand. In the absence of imidazoles, H117G-azurin reacted directly with 4-ethylphenol, this reaction was abolished in the presence of imidazoles. The enzymatic reduction of H117G-azurin by 4-EPMH was 40 times slower than that of wild-type azurin. The rate of this reaction was enhanced by some imidazoles, diminished by others. In all cases the reduction of H117G-azurin was irreversible. These results demonstrate that His117 is vital for electron transfer and effectively protects the copper site against aspecific reactions.

【 授权许可】

Unknown