title: Characterisation and amino acid sequence of cytochrome c-550 from Thiosphaera pantotropha.
abstract: A cytochrome c-550, with mid-point potential +265 mV, has been purified from Thiosphaera pantotropha. The cytochrome was recognised by antibodies to Paracoccus denitrificans cytochrome c-550, but the two proteins were not immunologically identical. Amino acid sequencing of the cytochrome c-550 showed 85.9% and 95.5% identities, respectively, with the cytochromes c-550 of P. denitrificans and Thiobacillus versutus; these are amongst the highest values reported for similarities between class I c-type cytochromes of the c2 group. These similarities are consistent with the published values of 85% for the overall DNA similarity of P. denitrificans and T. pantotropha, but contrast with published 16S rRNA analyses which indicate identity between T. pantotropha and P. denitrificans and 97.5% similarity of T. versutus with these two organisms. Analysis by plasma-desorption mass spectrometry of the peptide containing the haem-binding motif isolated from the apocytochrome has shown that an Hg atom binds to one or both of the two thiol groups.
authors.affiliation: Department of Biochemistry, Physiology and Microbiology, University of Ghent, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Samyn
authors.forename: B C
authors.initials: BC
authors.lastname: Berks
authors.forename: M D
authors.initials: MD
authors.lastname: Page
authors.forename: S J
authors.initials: SJ
authors.lastname: Ferguson
authors.forename: J J
authors.initials: JJ
authors.lastname: van Beeumen
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies; D001059:Apoproteins / Q000737:chemistry / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D003574:Cytochrome c Group / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D000939:Epitopes / Q000032:analysis; D006091:Gram-Negative Chemolithotrophic Bacteria / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010231:Paracoccus denitrificans / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013053:Spectrophotometry
chemical_list: D000906:Antibodies; D001059:Apoproteins; D003574:Cytochrome c Group; D000939:Epitopes; D046911:Macromolecular Substances; D010446:Peptide Fragments; C031732:cytochrome C-550