400 - A reexamination of the temperature dependence of spectral bands in the 600–780 nm region of cytochrome c

Abstract

Over the range of 12 to 50°C, the total oscillator strength of 697 ± 2 nm band of cytochrome c remains constant. Previous studies of the temperature lability of cytochrome c which relied solely on peak height as a measure of ligand integrity are suspect since, concomitant with a decrease in peak height, slight broadening also occurs, such that the total integrated intensity of the band remains constant. These results indicate that the methionine-80 residue of cytochrome c remains as a ligand, and that based solely on the “695” nm band, no isomerism can be detected spectroscopically between 12 and 50°C. In addition, a previously unreported band centered at 650 ± 4 nm was detected by computer analysis of this spectral region.