title: Characterization of the zinc-metalloprotein nature of rat spermatidal protein TP2.
abstract: Spermatidal transition protein, TP2, was purified from rat testes by Hg-affinity chromatography. The present study reports the details of the zinc-metalloprotein nature of TP2 by employing the 65 Zn-blotting technique. Chemical modification of cysteine by iodoacetic acid, and histidine by diethylpyrocarbonate, resulted in a near complete inhibition of 65Zn-binding to TP2. The 65Zinc-binding was localized to the V8 protease-derived N-terminal two-third polypeptide fragment. Circular dichroism spectroscopy studies of TP2 (zinc pre-incubated) and its V8 protease-derived polypeptide fragments revealed that the N-terminal fragment has a Type I-beta-turn spectrum, while the C-terminal fragment has a small but significant alpha-helical structure. EDTA altered the circular dichroism spectrum of TP2 and the N-terminal fragment (zinc binding domain) but not that of the C-terminal fragment.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore.
authors.forename: T K
authors.initials: TK
authors.lastname: Kundu
authors.forename: M R
authors.initials: MR
authors.lastname: Rao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D008297:Male; D008667:Metalloproteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D051381:Rats; D017208:Rats, Wistar; D012697:Serine Endopeptidases / Q000378:metabolism; D013087:Spermatids; D013737:Testis; D015032:Zinc / Q000378:metabolism*
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D008667:Metalloproteins; C053886:spermatid transition proteins; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D015032:Zinc