Purification of anti-HIV protein from purple fluid of the sea hare Bursatella leachii de Blainville.

The purple fluid of Bursatella leachii, already found to have anti-HIV activity, was selected and tested for purification and characterization of an anti-HIV protein. Only one fraction showed anti-HIV activity at the minimum inhibition concentration of 50 mg/ml. This purified anti-HIV protein has been named as "Bursatellanin-P" after the animal species Bursatella leachii. About 3 mg of the pure protein was obtained from 1000 ml of purple fluid. The anti-HIV activity increased by about 135-fold in the purified sample, as compared with the crude purple fluid. The purified protein, which showed anti-HIV activity, was a single unit with a molecular weight of 60 kDa. The protein was stable between pH 5.8 and 8.0. It lost its activity with heating at 60 degrees C for 10 minutes and also with extreme pH values of 2.0 or 10. The protein was resistant to digestion of proteinase K and mercaptoethanol.