A spectroscopic analysis of the Pro35 → Ala mutant of Rhodobacter capsulatus cytochrome c2 The strictly conserved Pro35 is not structurally essential

Abstract

Visible, near‐ultraviolet circular dichroic, near‐infrared and nuclear magnetic resonance spectroscopies show that the secondary and tertiary structures of the mutant Pro35 → Ala Rhodobacter capsulatus ferrocytochrome c2 are similar to the wild‐type protein. The near‐infrared spectrum shows that the methionine‐S – Fe‐heme bond is intact; however, a small red shift in the heme M transition of the near‐ultraviolet circular dichroic spectrum of the mutant indicates that the heme environment may differ slightly between the two proteins. This difference may be a consequence of changes in the ligand and hydrogen bonds of His17 [Gooley, P. R. & MacKenzie, N. E. (1990) FEBS Lett. 260, 225–228]. 1H a..