Direct observation of ligand migration within human hemoglobin at work.

ABSTRACT: Hemoglobin is one of the best-characterized proteins with respect to structure and function, but the internal ligand diffusion pathways remain obscure and controversial. Here we captured the CO migration processes in the tense (T), relaxed (R), and second relaxed (R2) quaternary structures of human hemoglobin by crystallography using a high-repetition pulsed laser technique at cryogenic temperatures. We found that in each quaternary structure, the photodissociated CO molecules migrate along distinct pathways in the α and β subunits by hopping between the internal cavities with correlated side chain motions of large nonpolar residues, such as α14Trp(A12), α105Leu(G12), β15Trp(A12), and β71Phe(E15). We also observe electron density evidence for the distal histidine [α58/β63His(E7)] swing-out

SUBMITTER: Shibayama N 

PROVIDER: S-EPMC7060717 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature