Marine biopolymers with cell specificity. II. Purification and characterization of agglutinins from mucus of windowpane flounder Lophopsetta maculata.

The windowpane flounder, Lophopsetta maculata, was found to have proteins in the body mucus which agglutinate mouse leukemia cells, L5784Y but not L1210. They also agglutinate rabbit and mouse erythrocytes, a marine yeast and a bacterium, and have weak activity against mouse sarcoma 180 cells, human B, guinea pig, and horse erythrocytes. The hemagglutinating activity was not affected by the treatment with 2-mercaptoethanol, trypsin, or pronase, but was inhibited by a high concentration of N-acetylneuraminic acid. The major active component was purified and found to be a protein having a molecular weight of 68 000 which dissociates into subunits of equal size (16 000). Isoelectrofocusing gave two sharp bands, close together, at pI 4.7 +/- 0.1. The protein contains high amounts of aspartic acid, glutamic acid and glycine, and very little histidine and half-cystine.