Maltose-binding lectin. No affinity is detected toward glucose. Has hemagglutinating activity against rabbit erythrocytes at 3.9 ug/ml. No carbonate dehydratase or trypsin inhibitor activity detected by measuring the hydrolysis of 4-nitrophenyl acetate or the inhibition of bovine trypsin-catalyzed hydrolysis of N-benzoyl-L-arginine ethyl ester, respectively. Loss of hemagglutinating activity by EDTA treatment. The activity is fully recovered by the addition of 5 mM Ca(2+) ions, but not with Mg(2+) and Mn 2(+). Hemagglutination activity is inhibited by maltose and its derivatives, with maltopentaose and maltohexaose being the best inhibitors followed by maltose and iso maltose. Not inhibited by glycoproteins. Full hemagglutinating activity after 3 hours of incubation at pH 3-9 at room temperature. The hemagglutinating activity is stable at 50 degrees Celsius up to 40 min, but decreases to 50% after 80 min. Homodimer; disulfide-linked. Expressed in tuber (at protein level). Not glycosylated. Belongs to the alpha-class carbonic anhydrase family. Despite overall sequence similarity to the typical alpha class carbonic anhydrases, lacks one of the three conserved catalytic zinc-ligand histidines.