Elements Of Signal Transduction

The natural extracellular ligands that bind and activate receptors are called first messengers. Major classes are listed in Table 12.1. A receptor (Hulme, 1990) is a biomacromolecule in on a cell that specifically recognizes and binds a ligand, which acts as a signal molecule, i.e. first messenger. Useful information concerning receptors and their ligands can be obtained from Receptor Database (http impact.nihs.go.jp RDB.html) and Relibase (http reliase.ebi.ac.uk ). Ligand receptor interactions...

Glycobiology Study Of Glycoproteinassociated Glycans

The covalent association between glycans (broadly oligo- and polysaccharides) and proteins or lipids are combined under the collective name glycoconjugates to which belong the proteoglycans and glycoproteins (glycosylated proteins). Figure 6.3 relates various classes of glycoconjugates. The carbohydrate part of glycosylated proteins can consist of one, several or many residues. Artificial glycosylated proteins used as model compounds for experimental purposes are called neoglycoproteins....

Lectincarbohydrate recognition ligand discrimination

The differential binding of glycoses to lectins depends on subtle changes in the disposition of amino acid side chains near the carbohydrate-binding sites. The sites are broad and shallow, with selectivity resulting from three factors 1) The epimeric OH that distinguishes particular glycoses, such as the 4-OH in Man-type versus Gal-type ligands, is involved in hydrogen bond and sometimes coordination bond to the lectins, so that the binding site directly reads out the differences among these...

Structure of antibody

The diversity of the immune response is impressive in that any foreign substances (antigens), small molecules or macromolecules, can elicit productions of appropriate proteins (antibodies) in response to diverse structures of antigens. In addition, the antibody response shows remarkable specificity. The specificity of the antibody-antigen interaction might be regarded as a model for molecular recognition. Antibodies belong to the class of serum glycoproteins called immunoglobulins (Igs), which...

Glycomics Proteoglycomic Approaches

17.4.1 Characterization of glycosylation sites The glycosylation sites of N-Linked glycopeptides in complex biological samples are generally identified by two methods, both involving the immobilization of glycopeptides on a solid support and subsequent release of N-linked glycopeptides. MS is then used to identify the N-linked glycosylation sites and quantify the relative abundance of glycopeptides using isotope-coded tags. The two methods differ in the mechanism by which the glycopeptides are...

Saccharide Biosynthesis And Glycobiology

13.1.1 Biosynthesis of biopolymer distributive versus processive Enzyme-catalyzed biosynthesis of a biopolymer may proceed by either distributive polymerization or processive polymerization. In biosynthetic polymerizations, the enzyme that has added a monomeric unit to the growing chain can either dissociate or recombine randomly with other growing termini or it can remain bound to the same chain and increases the chain length by additional units. Enzymes that dissociate between each addition...

Lectincarbohydrate recognition general

Several of the carbohydrate-binding proteins, though often completely unrelated in their functions, have similar structures that are characterized by the presence of two distinct globular domains with a deep cleft between them. Many ligand binding sites occur in the cleft where the domains approach each other (Quiocho, 1986). Thus carbohydrate-binding proteins can be divided into two major groups according to the topological features of the combining site (Rini, 1995). The proteins constituting...