Cleavage of the synaptobrevin/vesicle-associated membrane protein (VAMP) of the mouse brain by the recombinant light chain of Clostridium botulinum type B toxin.

The light chain of Clostridium botulinum type B toxin was expressed in Escherichia coli using the expression vector pEt-3a containing phage T7 promoter. The expressed protein was then purified by DEAE-cellulose and phosphocellulose chromatography and the proteolytic activity of the purified light chain was studied. The purified recombinant light chain cleaved synaptobrevin when mixed with the mouse brain microsome and the proteolytic activity of the light chain was inhibited if a metal chelating agent such as EDTA or 2,2'-dipyridyl was added. The recombinant light chain cleaved synaptobrevin more effectively than the native type B toxin. When the native toxin was trypinized and was reduced with DTT, its proteolytic activity was similar to that of the recombinant light chain.