期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1974
卷号：71
期号：4
页码：1339-1341
DOI：10.1073/pnas.71.4.1339
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The cobalt(II) derivative of the "blue" copper protein stellacyanin has been prepared, and its visible-ultraviolet spectrum is reported. Tryptophan fluorescence quenching and p-mercuribenzoate titration results strongly suggest that Co(II) and Cu(II) compete for the same stellacyanin binding site and that a cysteine sulfur atom is coordinated in both cases. This interpretation is supported by the finding of an intense band at 355 nm in Co(II)-stellacyanin attributable to a charge transfer transition of the RS- [->] Co(II) type. The visible absorption spectrum of Co(II)-stellacyanin exhibits band maxima at 540, 625, and 655 nm. These bands are attributable to d-d transitions originating in a high-spin Co(II) center. It is suggested that a correspondence exists between charge transfer bands observed at 355 and 300 nm in the Co(II) derivative to those found at 604 and 450 nm in the native protein. It is concluded that the intense 604-nm peak in Cu(II)-stellacyanin is attributable to a cys-S [->] Cu(II) charge transfer transition.
关键词：blue copper protein ; metal replacement ; electronic spectroscopy ; cysteine ligand
