title: Primary structure of potato kunitz-type serine proteinase inhibitor.
abstract: The serine proteinase inhibitor (PSPI-21) isolated from potato tubers (Solanum tuberosum L.) comprises two protein species with pI 5.2 and 6.3, denoted as PSPI-21-5.2 and PSPI-21-6.3, respectively. They were separated by anion exchange chromatography on a Mono Q FPLC column. Both species tightly inhibit human leukocyte elastase, whereas their interaction with trypsin and chymotrypsin is substantially weaker. The sequences of both PSPI-21-5.2 and PSPI-21-6.3 were determined by analysis of overlapping peptides obtained from the oxidized or reduced and S-pyridylethylated proteins after digestion with trypsin or pepsin. Both species of PSPI-21 are composed of two chains, named chains A and B, which are linked by a disulfide bridge between Cys(146) and Cys(157). The other disulfide bridge is located within the A chains between Cys(48) and Cys(97). The amino acid sequences of the large A chains of the two forms, consisting of 150 amino acids residues each, differ in a single residue at position 52. The small chains B, containing 37 and 36 residues in PSPI-21-6.3 and PSPI-21-5.2, respectively, have nine different residues. The entire amino acid sequences of the two inhibitors show a high degree of homology to the other Kunitz-type proteinase inhibitors from plants.
authors.affiliation: Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow.
authors.forename: T A
authors.initials: TA
authors.lastname: Valueva
authors.forename: T A
authors.initials: TA
authors.lastname: Revina
authors.forename: V V
authors.initials: VV
authors.lastname: Mosolov
authors.forename: R
authors.initials: R
authors.lastname: Mentele
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides; D006801:Humans; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D019272:Leukocyte Elastase / Q000037:antagonists & inhibitors; D013058:Mass Spectrometry; D010449:Peptide Mapping; D010455:Peptides; D010940:Plant Proteins; D021122:Protein Subunits; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000201:enzymology*; D014361:Trypsin Inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: D004220:Disulfides; D007527:Isoenzymes; C053865:Kunitz-type protease inhibitor, plant; D010455:Peptides; D010940:Plant Proteins; D021122:Protein Subunits; D014361:Trypsin Inhibitors; D019272:Leukocyte Elastase