title: Properties of thiol-specific anti-oxidant protein or calpromotin in solution.
abstract: We have isolated calpromotin, a protein reported abundant in human red cells and shown to be of significance for KCl transport. We show that calpromotin is identical to a radical scavenger protein, thiol-specific antioxidant protein (TSA). Calpromotin is known to exist partially as a large complex of identical subunits and partially as dimers probably held together by disulfide bridges. The stability of the high-molecular-weight form was studied by variations of pH and urea concentration. It is shown that the equilibrium between the large complex and the dimeric subunit is governed by the dissociation of a group with a pK value of about 7.5. Dissociation of the complex was also complete at 2.5 M urea, where no unfolding of the peptide chains was detectable.
authors.affiliation: The August Krogh Institute, University of Copenhagen, Denmark. PKristensen@aki.ku.dk
authors.forename: P
authors.initials: P
authors.lastname: Kristensen
authors.forename: D E
authors.initials: DE
authors.lastname: Rasmussen
authors.forename: B I
authors.initials: BI
authors.lastname: Kristensen
mesh_terms: D000595:Amino Acid Sequence; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002850:Chromatography, Gel; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes; D016166:Free Radical Scavengers / Q000097:blood / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010544:Peroxidases; D054464:Peroxiredoxins; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D017421:Sequence Analysis; D012996:Solutions; D014357:Trypsin / Q000378:metabolism; D014508:Urea / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D010446:Peptide Fragments; D011506:Proteins; D012996:Solutions; D014508:Urea; D010544:Peroxidases; D054464:Peroxiredoxins; D014357:Trypsin; D003545:Cysteine