title: The solution structure of the oxidized bovine microsomal cytochrome b(5) mutant V61H.
abstract: Using 1488 NOE constraints, 19 stereo-specific assignments, 13 pairs of H-bond constraints, and 140 pseudo-contact shift constraints, a family of 35 structures of bovine microsomal cytochrome b(5) mutant V61H has been obtained through the program PSEUDYANA. The family has been further refined by restrained energy minimization to give a family of final structures. The RMSD values of final structures with respect to the average structure are 0.45+/-0.11 and 0.96+/-0.10A for backbone and heavy atoms, respectively. The final Deltachi(ax) and Deltachi(rh) values are 2.34 x 10(-32) and -0.67 x 10(-32)m(3), respectively. The comparisons between the solution structures of mutant V61H and WT cytochrome b(5), and X-ray structure of the mutant V61H show that the global folding of the molecule in solution is unchanged and the side-chain of His61 deviates from the heme pocket and extends into the solvent like in its crystal structure. However, the helices around the heme pocket undergo outward global displacement while their local conformations are well maintained. Meanwhile, the heme ring shows a little off the heme pocket, which accounts for the lower stability of the mutant. Additionally, the axial ligand rings counterclockwise rotate around His39 N-Fe axis due to the mutation, which is confirmed by variation of the hyperfine shifts of the heme protons of V61H compared to those of WT cytochrome b(5).
authors.affiliation: State Key Laboratory of Bio-Organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, PR China.
authors.forename: Chunyang
authors.initials: C
authors.lastname: Cao
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Lin-Long
authors.initials: LL
authors.lastname: Xue
authors.forename: Jinbiao
authors.initials: J
authors.lastname: Ma
authors.forename: Yun-Hua
authors.initials: YH
authors.lastname: Wang
authors.forename: Houming
authors.initials: H
authors.lastname: Wu
authors.forename: Zhong-Xian
authors.initials: ZX
authors.lastname: Huang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D015786:Cytochromes b5 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006418:Heme / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D008861:Microsomes / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D017433:Protein Structure, Secondary; D011522:Protons
chemical_list: D008024:Ligands; D011522:Protons; D006418:Heme; D006639:Histidine; D015786:Cytochromes b5