Proton Magnetic Resonance Studies of Chromatium High-Potential Iron Protein
AUTOR(ES)
Phillips, W. D.
RESUMO
Contact-shifted nuclear magnetic resonances, arising from molecular paramagnetism, have been observed in both reduced and oxidized forms of the high-potential iron protein (HiPIP) isolated from Chromatium. Contact shifts of the reduced, formally diamagnetic form increase with temperature, indicating antiferromagnetic exchange coupling of the component iron atoms with thermal population of a magnetic state. In the oxidized form of HiPIP (formally S = 1/2), contact-shifted resonances attributed to the β-CH2 groups of two cysteine residues display approximate Curie law behavior, while contact-shifted resonances assigned to the two other cysteine residues continue to exhibit a temperature dependence characteristic of antiferromagnetic exchange coupling. A cluster model for the redox center of Chromatium HiPIP that appears compatible with the PMR and preliminary x-ray results4, 11 is discussed.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=283259Documentos Relacionados
- Photooxidation of the high-potential iron—sulfur center in chloroplasts
- A Comparison of Fe4S4 Clusters in High-Potential Iron Protein and in Ferredoxin
- Dependence of the rates of dissolution of the Fe4S4 clusters of Chromatium vinosum high-potential iron protein and ferredoxin on cluster oxidation state
- Crystal structures of photosynthetic reaction center and high-potential iron-sulfur protein from Thermochromatium tepidum: Thermostability and electron transfer
- Role of aromatic residues in stabilization of the [Fe4S4] cluster in high-potential iron proteins (HiPIPs): physical characterization and stability studies of Tyr-19 mutants of Chromatium vinosum HiPIP.
