Purification and partial characterization of paralytic shellfish poison-binding protein from Acanthocardia tuberculatum

A paralytic shellfish poison-binding protein (PSPBP) was purified 16.6-fold from the foot of the Moroccan cockles Acanthocardia tuberculatum. Using affinity chromatography, 2.5 mg of PSPBP showing homogeneity on sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) was obtained from 93 mg of crude extract. The purified PSPBP exhibits a specific activity of about 2.78 mU/mg proteins and has estimated molecular weight of 181 kDa. Observation of a single band equivalent to 88 kDa on SDS–PAGE under reducing conditions suggested it to be a homodimer. The optimal temperature and pH for the purified PSPBP were respectively 30 °C and 7.0.