title: Characterization of N-terminal amino group-heme ligation emerging upon guanidine hydrochloric acid induced unfolding of Hydrogenobacter thermophilus ferricytochrome c552.
abstract: Nonnative heme coordination structures emerging upon guanidine hydrochloric acid (GdnHCl) induced unfolding of Hydrogenobacter thermophilus ferricytochrome c552 were characterized by means of paramagnetic NMR. The heme coordination structure possessing the N-terminal amino group of the peptide chain in place of axial Met (His-Nterm form) was determined in the presence of GdnHCl concentrations in excess of 1.5 M at neutral pH. The stability of the His-Nterm form at pH 7.0 was found to be comparable with that of the bis-His form which has been recognized as a major nonnative heme coordination structure in cytochrome c folding/unfolding. Consequently, in addition to the bis-His form, the His-Nterm form is a substantial intermediate which affects the pathway and kinetics of the folding/unfolding of cytochromes c, of which the N-terminal amino groups are not acetylated.
authors: Department of Chemistry, University of Tsukuba, Tsukuba, 305-8571, Japan.
authors: Hulin
authors: H
authors: Tai
authors: Shin
authors: S
authors: Kawano
authors: Yasuhiko
authors: Y
authors: Yamamoto
mesh_terms: D000143:Acids / Q000737:chemistry*; D001419:Bacteria / Q000201:enzymology*; D002942:Circular Dichroism; D045304:Cytochromes c / Q000737:chemistry*; D019791:Guanidine / Q000737:chemistry*; D006418:Heme / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D019906:Nuclear Magnetic Resonance, Biomolecular; D011489:Protein Denaturation; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000143:Acids; D006418:Heme; D045304:Cytochromes c; D019791:Guanidine