Download MendeleyStability and Folding Kinetics of Structurally Characterized Cytochrome c-b(562).
Faraone-Mennella, J., Tezcan, F.A., Gray, H.B., Winkler, J.R.(2006) Biochemistry 45: 10504-10511
- PubMed: 16939202
- DOI: https://doi.org/10.1021/bi060242x
- Primary Citation of Related Structures:
2BC5 - PubMed Abstract:
The four-helix-bundle protein fold can be constructed from a wide variety of primary amino acid sequences. Proteins with this structure are excellent candidates for investigations of the relationship between folding mechanism and topology. The folding of cytochrome b(562), a four-helix-bundle heme protein, is hampered by heme dissociation. To overcome this complication, we have engineered a variant of cytochrome b(562) (cyt c-b(562)) featuring a c-type linkage between the heme and the polypeptide chain. The replacement of the native cyt b(562) leader sequence in this protein with that of a c-type cytochrome (cyt c(556)) led to high yields of fully matured and correctly folded cyt c-b(562). We have determined the X-ray crystal structure of cyt c-b(562) at 2.25 A and characterized its physical, chemical, and folding properties. These measurements reveal that the c-type linkage does not perturb the protein fold or reduction potential of the heme group. The covalent attachment of the porphyrin to the polypeptide does, however, produce a substantial change in protein stability and folding kinetics.
Organizational Affiliation:
Beckman Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA.
