Open AccessSpin-State Correlations in Near Infrared Spectroscopy of Cytochrome c′
Author(s) -
Martin D. Kamen,
Tomisaburo Kakuno,
Robert G. Bartsch,
S. Han
Publication year - 1973
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.70.6.1851
Subject(s) - infrared , absorption (acoustics) , absorption spectroscopy , infrared spectroscopy , chemistry , spectroscopy , spin states , analytical chemistry (journal) , spin (aerodynamics) , spectral line , rhodospirillum rubrum , materials science , physics , optics , inorganic chemistry , biochemistry , organic chemistry , chromatography , quantum mechanics , astronomy , composite material , thermodynamics , enzyme
Characteristic absorption spectra in the ultraviolet, visible, and near infrared regions are correlated with spin state in ferriheme proteins. Weak, diffuse bands in the near infrared exhibit maxima at about 1000-1100 nm (high spin) and at about 1450-1750 nm (low spin). In these and earlier studies such correlations have been established for several ferriheme proteins, but less extensively than in the more well-known cases of Soret and visible band maxima. We have strengthened the correlation in the near infrared by measurements of absorption spectra inRhodospirillum rubrum cytochromec ′, a variantc -type cytochrome that exhibits a pH-induced transition from high-spin to low-spin state as the pH varies from 6.3 to 13.1. Data are provided on extinction coefficients of characteristic absorption bands at various pH values, obtained by comparison with those measured under the same conditions for horse-heart ferricytochromec . It is concluded that good correlations of spin state with absorption behavior exist over the entire spectroscopic range from 250 to 2500 nm and that the basic assignments of absorption bands to in-plane charge transfer processes are consistent with these correlations.