@article {2509,
	title = {The affinity and specificity of Ca(2+)-binding sites of cytochrome-c peroxidase from Paracoccus denitrificans},
	journal = {Eur J Biochem},
	volume = {234},
	number = {3},
	year = {1995},
	note = {<p>0014-2956 (Print)0014-2956 (Linking)Journal ArticleResearch Support, Non-U.S. Gov{\textquoteright}t</p>
},
	month = {Dec 15},
	pages = {878-86},
	abstract = {<p>The binding of Ca2+ to the dihaem cytochrome-c peroxidase from Paracoccus denitrificans was analysed by following perturbations in the visible and 1H-NMR spectra of both haem groups. The enzyme contains at least two types of Ca(2+)-binding site. Site I is occupied in the isolated enzyme, binds Ca2+ with a redox-state-independent Kd of 1.2 microM and accommodates neither Mg2+ nor Mn2+. Site II is unoccupied in dilute solutions of the isolated oxidised enzyme and binds Ca2+ cooperatively with a Kd of 0.52 mM. In the mixed valence form, the binding affinity increases to resemble that of site I. The cooperativity was shown by -Ca2+ binding to site II, the titration of haem methyl 1H-NMR resonances, and a half-of-sites effect observed for modification of an essential histidine with diethylpyrocarbonate. These are all consistent with site II being situated at the interface between two monomers of a dimeric enzyme. Thus the equilibrium of binding to site II is a reflection of the equilibrium for dimerisation and conditions which shift that equilibrium towards the dimer, such as increased ionic strength or high protein concentration, also increase Ca2+ affinity. Binding of Ca2+ to site II is required for formation of the active high spin state at the peroxidatic haem.</p>
},
	keywords = {Ascorbic Acid/pharmacology, Binding Sites, Calcium/*metabolism/pharmacology, Cytochrome-c Peroxidase/*chemistry/metabolism, Edetic Acid/pharmacology, Egtazic Acid/pharmacology, Magnesium/metabolism, Magnetic Resonance Spectroscopy, Manganese/metabolism, Models, Chemical, Oxidation-Reduction, Paracoccus denitrificans/*enzymology, Protein Binding, Protein Conformation, Spectrophotometry, Substrate Specificity, Titrimetry},
	url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve\&db=PubMed\&dopt=Citation\&list_uids=8575448 },
	author = {Gilmour, R. and Prazeres, S. and McGinnity, D. F. and Goodhew, C. F. and Moura, J. J. and Moura, I. and Pettigrew, G. W.}
}
