N-acetyl-d-galactosamine/N-acetyl-d-glucosamine – recognizing lectin from the snailCepaea hortensis: purification, chemical characterization, cloning and expression inE. coli

Mining Invertebrate Natural Products for Future Therapeutic Treasure

This review focuses on biologically active entities from invertebrate sources, especially snails. The reader will encounter several categories of compounds from snails including glycosaminoglycans, peptides, proteins (glycoproteins), and enzymes which possess diverse biological activities. Among glycosaminoglycans, acharan sulfate which was isolated from a giant African snail Acahtina fulica is reviewed extensively. Conotoxins which are also called conopeptides are unique peptide mixtures from marine cone snail. Conotoxins are secreted to capture its prey, and currently have the potential to be highly effective drug candidates. One of the conotoxins is now in the market as a pain killer. Proteins as well as glycoproteins in the snail are known to be involved in the host defense process from an attack of diverse pathogens. Carbohydrate-degrading enzymes characterized and purified in snails are introduced to give an insight into the applicability in glycobiology research such as synthesis and structure characterization of glycoconjugates. It seems that simple snails produce very complicated biological compounds which could be an invaluable source in future therapeutics as well as research areas in natural medicine.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for the period 2005-2006

This review is the fourth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2006. The review covers fundamental studies, fragmentation of carbohydrate ions, method developments, and applications of the technique to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, glycated proteins, glycolipids from bacteria, glycosides, and various other natural products. There is a short section on the use of MALDI-TOF mass spectrometry for the study of enzymes involved in glycan processing, a section on industrial processes, particularly the development of biopharmaceuticals and a section on the use of MALDI-MS to monitor products of chemical synthesis of carbohydrates. Large carbohydrate-protein complexes and glycodendrimers are highlighted in this final section.

Biochemical and Structural Analysis of Helix pomatia Agglutinin

Helix pomatia agglutinin (HPA) is a N-acetylgalactosamine (GalNAc) binding lectin found in the albumen gland of the roman snail. As a constituent of perivitelline fluid, HPA protects fertilized eggs from bacteria and is part of the innate immunity system of the snail. The peptide sequence deduced from gene cloning demonstrates that HPA belongs to a family of carbohydrate-binding proteins recently identified in several invertebrates. This domain is also present in discoidin from the slime mold Dictyostelium discoideum. Investigation of the lectin specificity was performed with the use of glycan arrays, demonstrating that several GalNAc-containing oligosaccharides are bound and rationalizing the use of this lectin as a cancer marker. Titration microcalorimetry performed on the interaction between HPA and GalNAc indicates an affinity in the 10(-4) M range with an enthalpy-driven binding mechanism. The crystal structure of HPA demonstrates the occurrence of a new beta-sandwich lectin fold. The hexameric quaternary state was never observed previously for a lectin. The high resolution structure complex of HPA with GalNAc characterizes a new carbohydrate binding site and rationalizes the observed preference for alphaGalNAc-containing oligosaccharides.