title: Four disulfide bonds' allocation of Na+, K(+)-ATPase inhibitor (SPAI).
abstract: We have recently reported the primary structures of the three unique peptide inhibitors (SPAI-1, -2, and -3) against Na+, K(+)-ATPase which contained four disulfide bridges in common (Biochem. Biophys. Res. Commun. 164, 496 (1989)). The disulfide connectivities of SPAI were determined by the combination of amino acid analyses with the direct application to a gas-phase sequencer of its proteolytic fragments. The disulfide bond was identified by detection of phenylthiohydantoin derivatives of cystine and its decomposed product dehydroalanine. The four cysteine pairs were disclosed to be Cys20 to Cys49, Cys27 to Cys53, Cys36 to Cys48, and Cys42 to Cys57, all linked by disulfide bridge formation. The allocation pattern of these disulfide bonds was the same as that recently reported for human mucous proteinase inhibitor (EMBO J. 7, 345 (1988], though SPAI showed no proteinase inhibitory activity at all.
authors.affiliation: Tsukuba Research Laboratories, Eisai Co., Ltd, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Araki
authors.forename: M
authors.initials: M
authors.lastname: Kuwada
authors.forename: O
authors.initials: O
authors.lastname: Ito
authors.forename: J
authors.initials: J
authors.lastname: Kuroki
authors.forename: S
authors.initials: S
authors.lastname: Tachibana
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004220:Disulfides / Q000032:analysis; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007422:Intestines / Q000737:chemistry; D008969:Molecular Sequence Data; D011506:Proteins / Q000138:chemical synthesis* / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013552:Swine
chemical_list: D004220:Disulfides; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; C061401:SPAI-1 protein, Sus scrofa; C061403:SPAI-3 protein, Sus scrofa; C061402:SPAI-2 protein, Sus scrofa; D000254:Sodium-Potassium-Exchanging ATPase