Figure 1

Alignment of amino acid sequences of cytochrome b ₅ from various species (A), a close-up view of tertiary structure of human cytochrome b ₅ 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.