The peroxide complex of yeast cytochrome c peroxidase contains two distinct radical species, neither of which resides at methionine 172 or tryptophan 51.

摘要: The nature of the free radical species observed in peroxide complex yeast cytochrome c peroxidase is described for protein variants containing amino acid substitutions at Met-172 and Trp-51. As was case with mutations (Goodin, D.B., Mauk, A.G., Smith, M. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 1295-1299), Trp-51 can be substituted to give active enzyme. Phe-51-containing enzyme has a higher turnover rate than original exhibits an altered pH dependence. properties isotropic axial components (Hoffman, B.M., Roberts, J.E., Kang, C.H., Margoliash, E. (1981) J. Biol. Chem. 256, 6556-6564; Hori, H., Yonetani, T. (1985) 260, 349-355) EPR signal wild-type enzyme-peroxide complex, studied as function H2O2 stoichiometry, support proposals (Goodin et al. Hori Yonetani (1985), see above) that two distinct are formed, spin quantification shows always formed substoichiometric amounts. complexes proteins either or exhibit somewhat larger normal levels signal. In addition, these mutants unlike associated seen only 10 K not 90 K. Thus, neither considered molecular responsible signal, but both appear affect physical representing major species.