Alignment of amino acid sequences of cytochrome b
from various species (A), a close-up view of tertiary structure of human cytochrome b
around the heme-pocket with three conserved hydrophobic residues (Leu51, Ala59, and Gly67) and two heme axial ligands (His44 and His68) indicated (B), a close-up view around the heme pocket with acidic amino acid residues (C). (A) Amino acid sequences of cytochromes b5 from various species are aligned. Two heme axial ligands (His44 and His68) are indicated by an asterisk (*). On the other hand, corresponding positions to three target residues (Leu51, Ala59, and Gly67) in the present study are indicated by a cross (+). Amino acid sequences were obtained from [GenBank; NP_001164735 for rabbit b5, P00170 for horse b5, AAB67610 for rat b5, P56395 for mouse b5, AAA35729 for human b5, NP_776458 for bovine b5, BAA23735 for human OMb5, AAH72535 for rat OMb5; CAB01732 for C.elegans b5, P40312 for yeast b5, NP_001106739 for silkworm b5]. (B) Human cytochrome b5 NMR solution structure [PDB code: 2I96 model 1] is shown in a ribbon model with a bound heme b prosthetic group. In addition, three conserved residues (Leu51, Ala59, and Gly67) and two heme axial ligands (His44 and His68) are indicated. (C) Acidic amino acid residues located on the surface of the heme-binding domain (corresponding to LMWb5) are indicated.