Purification and N-terminal sequence of a serine proteinase-like protein (BMK-CBP) from the venom of the Chinese scorpion ( Buthus martensii Karsch)

A serine proteinase-like protein was isolated from the venom of Chinese red scorpion ( Buthus martensii Karsch) by combination of gel filtration, ion-exchange and reveres-phase chromatography and named BMK-CBP. The apparent molecular weight of BMK-CBP was identified as 33 kDa by SDS-PAGE under non-reducing condition. The sequence of N-terminal 40 amino acids was obtained by Edman degradation. The sequence shows highest similarity to proteinase from insect source. When tested with commonly used substrates of proteinase, no significant hydrolytic activity was observed for BMK-CBP. The purified BMK-CBP was found to bind to the cancer cell line MCF-7 and the cell binding ability was dose-dependent.