title: Identification and characterisation of Kunitz-type plasma kallikrein inhibitors unique to Oxyuranus sp. snake venoms.
abstract: As part of a wider study on Australian snake venom components, we have identified and characterised Kunitz-type protease inhibitors from the venoms of Oxyuranus scutellatus and Oxyuranus microlepidotus (Australian taipans) with plasma kallikrein inhibitory activity. Each inhibitor had a mass of 7 kDa and was purified from the venom as part of a protein complex. Mass spectrometry and N-terminal sequencing was employed to obtain amino acid sequence information for each inhibitor and a recombinant form of the O. scutellatus inhibitor, termed TSPI, was subsequently expressed and purified. TSPI was investigated for inhibition against a panel of 12 enzymes involved in haemostasis and estimates of the K(i) value determined for each enzyme. TSPI was found to be a broad spectrum inhibitor with most potent inhibitory activity observed against plasma kallikrein that corresponded to a K(i) of 0.057 ± 0.019 nM. TSPI also inhibited fibrinolysis in whole blood and prolonged the intrinsic clotting time. These inhibitors are also unique in that they appear to be found only in Oxyuranus sp. venoms.
authors.affiliation: The Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Brisbane 4029, Australia.
authors.forename: Stephen T H
authors.initials: ST
authors.lastname: Earl
authors.forename: Renee
authors.initials: R
authors.lastname: Richards
authors.forename: Lambro A
authors.initials: LA
authors.lastname: Johnson
authors.forename: Simone
authors.initials: S
authors.lastname: Flight
authors.forename: Steven
authors.initials: S
authors.lastname: Anderson
authors.forename: Ann
authors.initials: A
authors.lastname: Liao
authors.forename: John
authors.initials: J
authors.lastname: de Jersey
authors.forename: Paul P
authors.initials: PP
authors.lastname: Masci
authors.forename: Martin F
authors.initials: MF
authors.lastname: Lavin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001315:Australia; D004546:Elapid Venoms / Q000737:chemistry*; D017815:Elapidae / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D005342:Fibrinolysis / Q000187:drug effects; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D020842:Plasma Kallikrein / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D016415:Sequence Alignment; D013379:Substrate Specificity; D013916:Thrombelastography; D014914:Whole Blood Coagulation Time
chemical_list: D004546:Elapid Venoms; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D020842:Plasma Kallikrein