CARBOHYDRATE CONTENT AND MONOSACCHARIDE COMPOSITION OF RAPANA-THOMASIANA-GROSSE (GASTROPODA) HEMOCYANIN AND ITS STRUCTURAL SUBUNITS - COMPARISON WITH GASTROPODAN HEMOCYANINS

The hemocyanin of Rapana thomasiana grosse (marine snail, gastropod) i s a glycoprotein with a carbohydrate content of 8.9% (w/w) and monosac charide constituents xylose, fucose, 3-O-methylgalactose, mannose, gal actose, N-acetylgalactosamine and N-acetylglucosamine residues. The tw o structural subunits of this oxygen carrier, RHSS1 and RHSS2, are une venly glycosylated. On subtracting the carbohydrate contribution from the M(r) values of 250 and 450 kDa attributed to the two subunits, val ues of 2.18 x 10(5) daltons and 4.30 x 10(5) daltons were calculated f or the polypeptide part of the ''light'' and ''heavy'' subunits, respe ctively. Comparison of the monosaccharide compositions of gastropodan hemocyanins revealed qualitative similarities, as well as relationship s between the quantities, of the individual monosaccharides: Man great er than or equal to 3MeGal > GlcNAc greater than or equal to GalNAc an d Fuc greater than or equal to Xyl.