Spin cascade and doming in ferric hemes: Femtosecond X-ray absorption and X-ray emission studies.

ABSTRACT: The structure-function relationship is at the heart of biology, and major protein deformations are correlated to specific functions. For ferrous heme proteins, doming is associated with the respiratory function in hemoglobin and myoglobins. Cytochrome c (Cyt c) has evolved to become an important electron-transfer protein in humans. In its ferrous form, it undergoes ligand release and doming upon photoexcitation, but its ferric form does not release the distal ligand, while the return to the ground state has been attributed to thermal relaxation. Here, by combining femtosecond Fe K_α and K_β X-ray emission spectroscopy (XES) with Fe K-edge X-ray absorption near-edge structure (XANES), we demonstrate that the photocycle of ferric Cyt c is entirely due to a cascade

SUBMITTER: Bacellar C 

PROVIDER: S-EPMC7486745 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature