Open AccessCharacterisation and amino acid sequence of cytochrome c ‐550 from Thiosphaera pantotropha
Author(s) -
SAMYN Bart,
BERKS Ben C.,
PAGE M. Dudley,
FERGUSON Stuart J.,
BEEUMEN Jozef J.
Publication year - 1994
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1994.tb19974.x
Subject(s) - paracoccus denitrificans , cytochrome c , cytochrome , biochemistry , amino acid , peptide sequence , biology , chemistry , stereochemistry , microbiology and biotechnology , enzyme , gene , mitochondrion
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 c 2 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.