1H NMR studies of the effect of mutation at Valine45 on heme microenvironment of cytochrome b5.
1D and 2D (1)H NMR were employed to probe the effects on the heme microenvironment of cytochrome b(5) caused by the mutation from Val45 to Tyr45, His45 and Glu45. Compared with wild type (WT) cytochrome b(5), in all mutants the heme ring are CCW rotated relative to the imidazole planes of axial ligands and the angles beta between two axial ligand imidazole planes are not changed, being in agreement with the temperature dependence of the shifts of the heme protons. The ratios of heme isomers (major to minor) are smaller than that in WT. The 4-vinyl group of the heme in V45Y assumes cis-orientation, being similar to that of WT, while in V45E and V45H, both cis and trans orientation are found. The relationships between the structure and biological function of the mutants are discussed in terms of the geometry of heme and axial ligands, the hydrophobicity of heme pocket and the electrostatic potential of the heme-exposed area.
Cao
Chunyang
C
State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Feng Lin Lu (Road), Shanghai 200032, China.
Zhang
Qi
Q
Wang
Zhi-Qiang
ZQ
Wang
Yue-Feng
YF
Wang
Yun-Hua
YH
Wu
Houming
H
Huang
Zhong-Xian
ZX
D000818:Animals; D002417:Cattle; D015786:Cytochromes b5 / Q000737:chemistry* / Q000235:genetics; D004795:Enzyme Stability; D005973:Glutamine / Q000737:chemistry; D006418:Heme / Q000737:chemistry* / Q000235:genetics; D006639:Histidine / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008861:Microsomes / Q000201:enzymology; D015394:Molecular Structure; D009154:Mutation; D011487:Protein Conformation; D013696:Temperature; D014443:Tyrosine / Q000737:chemistry; D014633:Valine / Q000737:chemistry*
D007093:Imidazoles; D008024:Ligands; D005973:Glutamine; D014443:Tyrosine; D006418:Heme; D006639:Histidine; D015786:Cytochromes b5; D014633:Valine