title: Oligomerization of an avian thymic parvalbumin. Chemical evidence for a Ca(2+)-specific conformation.
abstract: CPV3, the third parvalbumin isoform to be identified in the chicken, is produced exclusively in the thymus gland. Although parvalbumins are typically cysteine-deficient, CPV3 contains two cysteine residues, at positions 18 and 72. The reported three-dimensional parvalbumin structures suggest that the side chain of cysteine-72 should be solvent-accessible. Accordingly, we find that CPV3 readily forms disulfide-linked oligomers in the absence of reducing agents. The reaction, employing either O2 or ferricyanide ion as the oxidant, is apparently restricted to the Ca(2+)-bound form of the protein. The differing reactivity of the Ca2+, Mg2+, and apo-forms has significant structural implications.
authors.affiliation: Biochemistry Department, University of Missouri, Columbia 65211.
authors.forename: R C
authors.initials: RC
authors.lastname: Hapak
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.forename: M T
authors.initials: MT
authors.lastname: Henzl
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002645:Chickens; D008274:Magnesium / Q000378:metabolism; D010320:Parvalbumins / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D013950:Thymus Gland / Q000378:metabolism*
chemical_list: D010320:Parvalbumins; D008274:Magnesium; D002118:Calcium