title: Trypsin and chymotrypsin inhibitor peptides from the venom of Chinese Daboia russellii siamensis.
abstract: Two trypsin inhibitors and one chymotrypsin inhibitor from Chinese Daboia russellii siamensis venom, denoted as CBPTI-1, CBPTI-2 and CBPTI-3 were purified, characterized and cloned from lyophilized venom-derived cDNA libraries. The N-terminus of CBPTI-1 was modified and not amenable to Edman degradation sequencing, however an internal partial sequence was found to be SGRCRGHLRRIYYNPDSNKCE. The N-termini of CBPTI-2 and CBPTI-3 were unmodified and their partial sequences were established as HDRPTFCNLAPESGRCRAH and HDRPKFCYLPADPGECMAYIRSFYYDS respectively. From cloning studies CBPTI-1 was found to consist of 66 amino acid residues, while CBPTI-2 and CBPTI-3 precursors consist of 60 amino acid residues, including 6 cysteine residues. Another cDNA sequence (CBPTI-4) was also obtained. Alignment of cDNA sequences showed that CBPTI-3 exhibited similar sequence homology to CBPTI-4 cDNA except for an 8 nucleotide deletion in the open-reading frame. CBPTI-1 and CBPTI-2 were demonstrated to be potent trypsin inhibitors, but were also shown to be effectively potent in chymotrypsin inhibition. The K(i) values of CBPTI-1 and CBPTI-2 for trypsin inhibition were 4.07 × 10(-7) M and 6.66 × 10(-7) M, respectively, and they were non-competitive in their activity. CBPTI-3 showed chymotrypsin inhibition activity with a K(i) value of 2.55 × 10(-9) M, but did not show trypsin inhibitor activity.
authors.affiliation: Biomedical Sciences Research Institute, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, UK.
authors.forename: Chun-teng
authors.initials: CT
authors.lastname: Guo
authors.forename: Stephen
authors.initials: S
authors.lastname: McClean
authors.forename: Chris
authors.initials: C
authors.lastname: Shaw
authors.forename: Ping-fan
authors.initials: PF
authors.lastname: Rao
authors.forename: Ming-yu
authors.initials: MY
authors.lastname: Ye
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Bjourson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003001:Cloning, Molecular; D004546:Elapid Venoms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis / Q000378:metabolism*; D017840:Daboia / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014357:Trypsin / Q000032:analysis / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004546:Elapid Venoms; D010446:Peptide Fragments; D014361:Trypsin Inhibitors; D002918:Chymotrypsin; D014357:Trypsin