A galactose-specific lectin from the red marine alga Ptilota filicina

A lectin from the red marine alga Ptilota filicina (PFL) was isolated by affinity chromatography on cross-linked guar gum. PFL agglutinated native and papain-treated human erythrocytes with preference for type O erythrocytes. The lectin was inhibited by galactose and its derivatives. The most potent inhibitors were p-Nitrophenyl-N-acetyl-alpha- and beta-D-galactosaminide, Porcine stomach mucin, bovine submaxillary gland mucin and asialo bovine mucin were also inhibitory. The M-r of PFL, determined by gel filtration, was 56,900. SDS-PAGE gave one band with a subunit M-r of 19,320, indicating the native protein to be a rimer of apparently identical subunits. PFL was shown to be rich in acidic and hydroxyl amino acids but low in basic amino acids. The ten N-terminal amino acids were Asx-Thr-Lys-Thr-Tyr-Leu-Leu-Ala-. (C) 1998 Elsevier Science Ltd. All rights reserved.