NDLI: Preparation and Spectroscopic Studies of Cobalt(II)-Stellacyanin

Content Provider	PubMed Central
Author	Mcmillin, David R. Holwerda, Robert A. Gray, Harry B.
Abstract	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.
Starting Page	1339
File Format	PDF
ISSN	10916490
e-ISSN	10916490
Journal	Proceedings of the National Academy of Sciences of the United States of America
Issue Number	4
Volume Number	71
Language	English
Publisher Date	1974-04-01
Access Restriction	Open
Subject Keyword	Research in Higher Education
Content Type	Text
Resource Type	Article
Subject	Multidisciplinary

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Preparation and Spectroscopic Studies of Cobalt(II)-Stellacyanin