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Toxins 2016, 8(2), 36;

Structure-Activity Relationship of Chlorotoxin-Like Peptides

International Center for Chemical and Biochemical Sciences (ICCBS), HEJ Research Institute of Chemistry, University of Karachi, Karachi-75270, Pakistan
Interfaculty Institute of Biochemistry (IIB), University of Tuebingen, Hoppe-Seyler Str. 4, Tuebingen D-72076, Germany
Venom Evolution Laboratory, School of Biological Sciences, University of Queensland, Brisbane, QLD 4072, Australia
Present address: Dow International Medical College, Dow University of Health Sciences, Karachi-75270, Pakistan
Author to whom correspondence should be addressed.
Academic Editors: Rong Chen and Yingliang Wu
Received: 2 November 2015 / Revised: 18 January 2016 / Accepted: 19 January 2016 / Published: 2 February 2016
(This article belongs to the Special Issue Animal Toxins and Biological Ion Channels)
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Animal venom (e.g., scorpion) is a rich source of various protein and peptide toxins with diverse physio-/pharmaco-logical activities, which generally exert their action via target-specific modulation of different ion channel functions. Scorpion venoms are among the most widely-known source of peptidyl neurotoxins used for callipering different ion channels, such as; Na+, K+, Ca+, Cl, etc. A new peptide of the chlorotoxin family (i.e., Bs-Tx7) has been isolated, sequenced and synthesized from scorpion Buthus sindicus (family Buthidae) venom. This peptide demonstrates 66% with chlorotoxin (ClTx) and 82% with CFTR channel inhibitor (GaTx1) sequence identities reported from Leiurus quinquestriatus hebraeus venom. The toxin has a molecular mass of 3821 Da and possesses four intra-chain disulphide bonds. Amino acid sequence analysis of Bs-Tx7 revealed the presence of a scissile peptide bond (i.e., Gly-Ile) for human MMP2, whose activity is increased in the case of tumour malignancy. The effect of hMMP2 on Bs-Tx7, or vice versa, observed using the FRET peptide substrate with methoxycoumarin (Mca)/dinitrophenyl (Dnp) as fluorophore/quencher, designed and synthesized to obtain the lowest Km value for this substrate, showed approximately a 60% increase in the activity of hMMP2 upon incubation of Bs-Tx7 with the enzyme at a micromolar concentration (4 µM), indicating the importance of this toxin in diseases associated with decreased MMP2 activity. View Full-Text
Keywords: CFTR; chlorotoxin; chloride channel; MMP2; peptidyl-inhibitors; scorpion venom CFTR; chlorotoxin; chloride channel; MMP2; peptidyl-inhibitors; scorpion venom

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Ali, S.A.; Alam, M.; Abbasi, A.; Undheim, E.A.B.; Fry, B.G.; Kalbacher, H.; Voelter, W. Structure-Activity Relationship of Chlorotoxin-Like Peptides. Toxins 2016, 8, 36.

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