Characterization and gene organization of Taiwan banded krait (Bungarus multicinctus) gamma-bungarotoxin |
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Authors: | Chang Long-Sen Chung Charling Wu Bin-Nan Yang Chen-Chung |
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Affiliation: | (1) Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan;(2) Department of Pharmacology, Kaohsiung Medical University, Kaohsiung, 807, Taiwan;(3) Department of Life Sciences, National Tsing-Hua University, Hsinchu, 300, Taiwan |
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Abstract: | -Bungarotoxin was isolated from Bungarus multicinctus (Taiwan banded krait) venom using a combination of chromatography on a SP-Sephadex C-25 column and a reverse-phase high-performance liquid chromatography column. Circular dichroism (CD) measurement revealed that its secondary structure was dominant with -sheet structure as is that of snake venom -neurotoxins and cardiotoxins. -Bungarotoxin exhibits activity on inhibiting the binding of [3H]quinuclidinyl benzilate to the M2 muscarinic acetylcholine receptor subtype, and competes weakly with radioiodinated -bungarotoxin for binding to the Torpedo nicotinic acetylcholine receptor. Moreover, the toxin inhibits collagen-induced platelet aggregation, with an IC50 of approximately 200 nM. The genomic DNA encoding the -bungarotoxin precursor is amplified by polymerase chain reaction (PCR). The gene is organized with three exons separated by two introns, and shares virtually identical overall organization with those reported for -neurotoxin and cardiotoxin genes, including similar intron insertions. The intron sequences of these genes share sequence identity up to 85%, but the exon sequences are highly variable. These observations suggest that -bungarotoxin, -neurotoxins, and cardiotoxins originate from a common ancestor, and the evolution of these genes shows a tendency to diversify the functions of snake venom proteins. |
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Keywords: | /content/w85lnq6p818v3285/xxlarge947.gif" alt=" gamma" align=" MIDDLE" BORDER=" 0" >-Bungarotoxin neurotoxicity platelet aggregation gene organization |
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