Kinetic studies on the effect of the heme iron(III) on the protein folding of ferricytochrome c.
The three-dimensional conformation of ferricytochrome c results from specific folding of the polypeptide chain around the covalently bound heme so that His-18 and Met-80 are axially coordinated to the Fe(III). The Fe(III)-free, porphyrin protein has an intrinsic viscosity, sedimentation coefficient, and circular dichroism indicative of a compact, globular protein conformation comparable to the holoprotein. Both the porphyrin protein and ferricytochrome c are reversibly denatured by guanidinium chloride. Refolding of the porphyrin protein occurs in essentially a single, exceptionally rapid kinetic phase (tau = 14 ms, 0.75 M guanidinium chloride, pH 6.5, 25 degrees C); whereas refolding of ferricytochrome c occurs in two slower kinetic phases (TAU 1 = 0.10 S, TAU 2 = 20 S) UNDER COMPARABLE CONDITIONS. The presence of Fe(III) in the metalloporphyrin of ferricytochrome c thus has a major effect on the protein folding kinetics. The slow kinetic phase is evidently due to this effect of Fe(III) and not to the slow cis-trans isomerism of the peptide bond of proline residues as has been suggested.[1]References
- Kinetic studies on the effect of the heme iron(III) on the protein folding of ferricytochrome c. Henkens, R.W., Turner, S.R. J. Biol. Chem. (1979) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
