title: HV-BBI--a novel amphibian skin Bowman-Birk-like trypsin inhibitor.
abstract: Here we describe the isolation of a novel C-terminally amidated octadecapeptide--SVIGCWTKSIPPRPCFVK-amide--that contains a disulphide loop between Cys(5) and Cys(15) that is consistent with a Bowman-Birk type protease inhibitor, from the skin secretion of the Chinese Bamboo odorous frog, Huia versabilis. Named HV-BBI, the peptide is encoded by a single precursor of 62 amino acid residues whose primary structure was deduced from cloned skin cDNA. The precursor exhibits the typical organization of that encoding an amphibian skin peptide with a highly-conserved signal peptide, an intervening acidic amino acid residue-rich domain and a single HV-BBI-encoding domain located towards the C-terminus. A synthetic replicate of HV-BBI, with the wild-type K (Lys-8) residue in the presumed P1 position, was found to be a potent inhibitor of trypsin with a K(i) just slightly less than 19 nM. Substitution at this site with R (Arg) resulted in a significant reduction in potency (K(i) 57 nM), whereas replacement of K with F (Phe) resulted in the complete abolition of trypsin inhibitory activity. Thus, HV-BBI is a potent inhibitor of trypsin and the lysyl (K) residue that occupies the P1 position appears to be optimal for potency of action against this protease.
authors.affiliation: Molecular Therapeutics Research, School of Pharmacy, Queen's University, McClay Research Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK.
authors.forename: Ganhong
authors.initials: G
authors.lastname: Song
authors.forename: Mei
authors.initials: M
authors.lastname: Zhou
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Tianbao
authors.initials: T
authors.lastname: Chen
authors.forename: Brian
authors.initials: B
authors.lastname: Walker
authors.forename: Chris
authors.initials: C
authors.lastname: Shaw
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D011487:Protein Conformation; D011898:Ranidae / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*
chemical_list: D018076:DNA, Complementary; C529612:HV-BBI peptide, Huia versabilis; D010455:Peptides; D014361:Trypsin Inhibitors