title: Biochemical evidence of specific trypsin-chymotrypsin inhibitors in the rhynchobdellid leech, Theromyzon tessulatum.
abstract: The presence of two specific trypsin-chymotrypsin inhibitors from head parts of the rhynchobdellid leech Theromyzon tessulatum is reported. Two proteins, anti-trypsin chymotrypsin A (ATCA; 14636.6 +/- 131 Da) and anti-trypsin-chymotrypsin B (ATCB; 14368 +/- 95 Da) were purified by size exclusion and anion-exchange chromatography followed by reversed-phase HPLC. Based on amino-acid composition, N-terminal sequence determination (MELCELGQSCSRD-NPQPSNM), matrix assisted laser desorption-time of flight measurement (MALDI-TOF), trypsin mapping comparison, inhibition constant determination (Ki), and influence on amidolytic activity of different serine proteases, it is demonstrated that ATCA and ATCB are novel and highly potent serine-protease inhibitors of trypsin and chymotrypsin (ATCA: 350fM towards trypsin and chymotrypsin; ATCB: 400 and 75 fM towards trypsin and chymotrypsin, respectively). It is further surmised that ATCA and ATCB are linked, in that ATCB would lead to the formation of ATCA after loss of few amino acid residues.
authors.affiliation: Centre de Biologie Cellulaire, Laboratoire de Phylogénie moléculaire des Annélides EA DRED 1027, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France.
authors.forename: V
authors.initials: V
authors.lastname: Chopin
authors.forename: G
authors.initials: G
authors.lastname: Stefano
authors.forename: M
authors.initials: M
authors.lastname: Salzet
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D019075:Electrophoresis, Capillary; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D007865:Leeches / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D020539:Sequence Analysis, Protein; D015842:Serine Proteinase Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity; D014357:Trypsin / Q000187:drug effects*; D014361:Trypsin Inhibitors / Q000737:chemistry
chemical_list: D000596:Amino Acids; D004791:Enzyme Inhibitors; D010455:Peptides; D015842:Serine Proteinase Inhibitors; D014361:Trypsin Inhibitors; D002918:Chymotrypsin; D014357:Trypsin