Document Detail


Domain Swapping of the Heme and N-terminal α-Helix in Hydrogenobacter thermophilus Cytochrome c(552) Dimer.
MedLine Citation:
PMID:  23035813     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Oxidized horse cytochorme c (cyt c) has been shown to oligmerize by domain swapping its C-terminal helix successively. We show that the structural and thermodynamic properties of dimeric Hydrogenobacter thermophilus (HT) cytochrome c(552) (cyt c(552)) and dimeric horse cyt c are different, although both proteins belong to the cyt c superfamily. Optical absorption and CD spectra of oxidized dimeric HT cyt c(552) were identical to the corresponding spectra of its monomer. Dimeric HT cyt c(552) exhibited a domain-swapped structure, where the N-terminal α-helix together with the heme was exchanged between protomers. Since a relatively strong H-bond network was formed at the loop around the heme-coordinated Met, the C-terminal α-helix did not dissociate from the rest of the protein in dimeric HT cyt c(552). The packing of the amino acid residues important for thermostability in monomeric HT cyt c(552) were maintained in its dimer, and thus, dimeric HT cyt c(552) exhibited high thermostability. Although the midpoint redox potential shifted from 240 ± 2 to 213 ± 2 mV by dimerization, it was maintained relatively high. Ethanol has been shown to decrease both the activation enthalpy and activation entropy for the dissociation of the dimer to monomers from 140 ± 9 to 110 ± 5 kcal/mol and 310 ± 30 to 270 ± 20 cal/(mol∙K), respectively. Enthalpy change for the dissociation of the dimer to monomers was positive (14 ± 2 kcal/mol per protomer unit). These results give new insights into factors governing the swapping region and thermodynamic properties of domain swapping.
Authors:
Yugo Hayashi; Satoshi Nagao; Hisao Osuka; Hirofumi Komori; Yoshiki Higuchi; Shun Hirota
Related Documents :
24236883 - Novel serine protease inhibitors.
23069613 - Role and significance of beta-glucosidases in the hydrolysis of cellulose for bioethano...
2998353 - Cys154 is important for lac permease activity in escherichia coli.
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-4
Journal Detail:
Title:  Biochemistry     Volume:  -     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Flow cytometric identification of Mamiellales clade II in the Southern Atlantic Ocean.
Next Document:  Design, Synthesis, and Anti-tobacco Mosaic Virus (TMV) Activity of Phenanthroindolizidines and Their...