Question

What is the glycan structure on horse blood and the lectin structure of small kidney beans?

Answer 1

The structure of all of the glycans has been established by combining methylation analysis, mass spectrometry and 400-MHz 1H-NMR spectroscopy. From the obtained results, it appears that the two glycans of Tf 5b variant are, like in human serotransferrin, of the N-acetyllactosaminic biantennary type, fully silylated by two residues of N-acetylneuraminic acid (Neu5Ac; glycan type I).

In contrast, in addition to this structure, two N-acetyllactosaminic biantennary isomeric structures named type II-A and type II-B silylated by one Neu5Ac residue and one N-acetyl-4-O-acetylneuraminic acid [Neu(4,5)Ac2] residue located either at Gal6 or 6′ and one N-acetyllactosaminic biantennary structure (named type III) sialylated by two residues of Neu(4,5)Ac2, were identified in variants Tf 2a and Tf 4b.

Red kidney beans (Phaseolus vulgaris) contain significant amounts of lectins which have both beneficial and detrimental biological properties. Lectins are carbohydrate-binding glycoproteins that can react specifically with human blood cells, preferentially agglutinate malignant cells, and undergo mitogenic stimulation of lymphocytes.

Some lectins are resistant to heat and proteolytic enzymes and can enter the circulatory system intact. Phytohaemagglutinin (PHA)—a lectin isolated from the red kidney bean—consists of four subunits with a molecular weight of 125 kDa. This bioactive compound has been partially purified by affinity chromatography using Affi-gel Blue. PHA has been shown to inhibit the viral enzymes, immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT), and α- and β-glucosidases.