Unfolding cytochromes c-b562 and Rd apo b562.

Unfolding cytochromes c-b562 and Rd apo b562.
J Inorg Biochem. 2020 Aug 10;211:111209
Authors: Kozak JJ, Gray HB, Garza-López RA
Abstract
We have analyzed the early stages of unfolding of cytochromes c-b562 (PDB ID: 2BC5) and Rd apo b562 (PDB ID: 1YYJ). Our geometrical approach proceeds from an analysis of the crystal structure reported for each protein. We quantify, residue-by-residue and region-by-region, the spatial and angular changes in the structure as the protein denatures, and quantify differences that result from the seven residues that differ in the two proteins. Using two independent analyses, one based on spatial metrics and the second on angular metrics, we establish the order of unfolding of the five helices in cyt c-b562 and the four helices in the apo protein. For the two helices nearest the N-terminal end of both proteins, the ones in the apo protein unfold first. For the two helices nearest the C-terminal end, the interior helix of the apo protein unfolds first, whereas the terminal helix of the holo protein unfolds first. Excluded-volume effects (repulsive interactions) are minimized in turning regions; the overall range in Δ values is Δ = 36.3 Å3 for cyt c-b562 and Δ = 36.6 Å3 for the apo protein, whereas the span for all 20 amino acids is Δ = 167.7 Å3. As our work indicates that the interior helix of cytochrome c-b562 is the first to fold, we suggest that this helix protects the heme from misliga...

Source: Journal of Inorganic Biochemistry - August 9, 2020 Category: Biochemistry Authors: Kozak JJ, Gray HB, Garza-López RA Tags: J Inorg Biochem Source Type: research