Open AccessHigh‐resolution crystal structures of the solubilized domain of porcine cytochrome b 5
Author(s) -
Hirano Yu,
Kimura Shigenobu,
Tamada Taro
Publication year - 2015
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s1399004715009438
Subject(s) - chemistry , protonation , crystallography , hydrogen bond , redox , electron transfer , cytochrome b5 , cytochrome , crystal structure , electron transport chain , ligand (biochemistry) , heme , cytochrome c , stereochemistry , photochemistry , molecule , enzyme , inorganic chemistry , biochemistry , mitochondrion , receptor , ion , organic chemistry
Mammalian microsomal cytochrome b 5 has multiple electron‐transfer partners that function in various electron‐transfer reactions. Four crystal structures of the solubilized haem‐binding domain of cytochrome b 5 from porcine liver were determined at sub‐angstrom resolution (0.76–0.95 Å) in two crystal forms for both the oxidized and reduced states. The high‐resolution structures clearly displayed the electron density of H atoms in some amino‐acid residues. Unrestrained refinement of bond lengths revealed that the protonation states of the haem propionate group may be involved in regulation of the haem redox properties. The haem Fe coordination geometry did not show significant differences between the oxidized and reduced structures. However, structural differences between the oxidized and reduced states were observed in the hydrogen‐bond network around the axial ligand His68. The hydrogen‐bond network could be involved in regulating the redox states of the haem group.