THE COMPLETE AMINO-ACID-SEQUENCE CONFIRMS THE PRESENCE OF PSEUDOAZURIN IN THIOSPHAERA-PANTOTROPHA

Citation
C. Chan et al., THE COMPLETE AMINO-ACID-SEQUENCE CONFIRMS THE PRESENCE OF PSEUDOAZURIN IN THIOSPHAERA-PANTOTROPHA, Biochemical journal, 308, 1995, pp. 585-590
Citations number
27
Categorie Soggetti
Biology
Journal title
ISSN journal
02646021
Volume
308
Year of publication
1995
Part
2
Pages
585 - 590
Database
ISI
SICI code
0264-6021(1995)308:<585:TCACTP>2.0.ZU;2-D
Abstract
The complete amino acid sequence, obtained by direct protein sequencin g, of the pseudoazurin from Thiosphaera pantotropha is reported. It sh ows sequence identities varying from 46 to 66% with previously sequenc ed pseudoazurins. Previously identified conserved residues with key fu nctions in pseudoazurins are found in the protein from T. pantotropha with the exception of glycine-39, the carbonyl group of which has been considered as a ligand to the copper, which is replaced by a serine r esidue. Electrospray-ionization MS (ESI-MS) has shown that pseudoazuri n from T. pantotropha often contains two polypeptide species differing in molecular mass by 16 Da, presumably owing to oxidation of a methio nine residue to a sulphoxide derivative. These two species have differ ent endoproteinase Arg-C digestion patterns. Conditions for ESI-MS wer e identified that permitted either the retention or the loss of the si ngle copper ion associated with the pseudoazurin. The aberrant tendenc y of T. pantotropha pseudoazurin to form a disulphide-bridged dimer on SDS/PAGE under some conditions is described.