CHARACTERIZATION OF A NATURAL HEMAGGLUTININ IN THE SERUM OF A FRESH-WATER CRAB PARATHELPHUSA-HYDRODROMUS (HERBST)

A naturally occurring hemagglutinin (HA) was detected in the serum of the freshwater crab Parathelphusa hydrodromus using mammalian erythroc ytes (RBC) as indicator cells. The serum gave the highest HA titer wit h rabbit RBC. In cross adsorption tests, this RBC type completely adso rbed all HA activities from serum. An analysis of the physico-chemical properties of HA showed it to be specifically dependent on the presen ce of Ca2+ for its activity, irreversibly sensitive to EDTA, stable be tween pH 7.5 and 10.0, and heat-labile. Further studies demonstrated t hat the HA is proteinaceous as it was precipitable by conventional dep roteinizing agents, and susceptible to the action of proteases and 2-m ercaptoethanol. HA-inhibition assays performed with 44 carbohydrates r evealed that the serum HA was specific for non-reducing terminal gluco se with alpha 1-2 glycosidic linkage. Thus this agglutinin appears to be unique among all the known crustacean agglutinins.