title: Primary structure of a 21-kD protein from potato tubers.
abstract: A 21-kD protein isolated earlier from potato tubers (Solanum tuberosum L.) has two isoforms, with pI 6.3 and 5.2, which were separated by fast protein ion-exchange chromatography on a Mono Q column. The primary structures of the two forms consisted of 187 and 186 amino acid residues. Both isoforms are composed of two polypeptide chains, designated A and B, linked by a single disulfide bond between Cys-146 of the A chain and Cys-7 of the B chain. The amino acid sequences of the A chains of the two forms, consisting of 150 residues each, differ in a single amino acid residue at position 52 (Val --> Ile), while the B chains, containing 37 and 36 residues, respectively, have substitutions at nine positions (Leu-8 --> Ser-8, Lys-25--Asp-26 --> Asn-25--Glu-26, Ile-31--Ser-32 --> Val-31--Leu-32, Lys-34--Gln-35--Val-36--Gln-37 --> Gln-34--Glu-35--Val-36). Both isoforms form stable inhibiting complexes with human leukocyte elastase and are less effective against chymotrypsin and trypsin.
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, 117071, Russia. inbio@glas.apc.org.
authors.forename: T A
authors.initials: TA
authors.lastname: Valueva
authors.forename: T A
authors.initials: TA
authors.lastname: Revina
authors.forename: G V
authors.initials: GV
authors.lastname: Kladnitskaya
authors.forename: V V
authors.initials: VV
authors.lastname: Mosolov
authors.forename: P
authors.initials: P
authors.lastname: Mentele
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D020033:Protein Isoforms / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000737:chemistry*
chemical_list: C402946:21-KDa protein, Solanum tuberosum; D010940:Plant Proteins; D020033:Protein Isoforms