Analytical studies on crotamine hydrochloride. |
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Authors: | J R Giglio |
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Institution: | Faculdade de Medicina, Universidade de São Paulo, Departamento de Bioquímica, 14.100 Ribeirão Preto—SP, Brazil |
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Abstract: | The neurotoxin crotamine, which is a basic low molecular weight protein, was isolated, in the form of its hydrochloride, from a South Brazilian rattlesnake (Crotalus durissus crotaminicus, Crotalus durissus terrificus) venom.Disc electrophoresis, carried out in 7% acrylamide by the method of Reisfeld, at pH 4.5, showed a single band for the purified toxin.The toxin showed the following amino acid composition: Asx2, Ser3, Glx2, Pro3, Gly5, Cys5, Met1, Ileu1, Leu1, Tyr1, Phe2, Trp2, Lys9, His2, and Arg2, which corresponds to a minimum molecular weight of 4760. This assignment of minimum molecular weight is supported by the recovery of 1.0 mole of N-terminal of crotamine by the Sanger dinitrophenol (DNP) method, 1.0 mole of by the Udenfriend method, and by uv analysis, which gave a value of 4820. The odd number of half-cystine residues () cannot be explained on the basis of available analytical data.Tyrosine was the only amino-terminal residue detectable by the Sanger DNP method. Glycine was identified as the only carboxyl-terminal residue by the hydrazinolysis method of Akabori and by release upon treatment with yeast carboxypeptidase.The H+ electrometric and Cl? complexometric titrations of crotamine hydrochloride showed that about 13 moles of HCl are bound per 4760 g of the free base. |
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