A particularly labile Asp‐Pro bond in the green mamba muscarinic toxin MTX2. Effect of protein conformation on the rate of cleavage

[摘要]

The single Asp⁵³-Pro⁵⁴ bond of the MTX2 toxin from the mamba snake Dendroaspis angusticeps is rapidly and efficiently cleaved in acidic solution (pH 1.5–2.5) at 45°C. Unfolding of the toxin slows down the cleavage reaction by several times. Modelling studies indicate that the native toxin conformation can catalyse the Asp⁵³-Pro⁵⁴ bond cleavage. The implications of this study are: (i) cleavage of Asp-Pro bond for sequence determination may occur better in absence than in presence of denaturant, (ii) mild acid conditions, commonly used in NMR structure determinations, may irreversibly affect the structural integrity of Asp--Pro containing peptides and proteins.

[学科分类] 生物化学/生物物理

[关键词] Peptide bond cleavage;Asp-Pro bond;Protein conformation;Protein degradation;Peptide fragment;Muscarinic toxin;CZE;capillary zone electrophoresis;MTX2;Dendroaspis angusticeps muscarinic toxin 2;PE-MTX2;pyridine-ethylated MTX2