Carbohydrates on proteins

Mateus, N., Carvalho, E., Luis, C., de Freitas, V. A. P. (2004a). Influence of the tannin structure towards the disruption effect of carbohydrates on protein-tannin aggregates. Anal Chim. Acta, 513, 135-140. 

The presence of carbohydrate on protein molecules protects them from dena-turation. For example, bovine RNase A is more susceptible to heat denaturation than its glycosylated counterpart RNase B. Several other studies have shown that sugar-rich glycoproteins are relatively resistant to proteolysis (splitting of polypeptides by enzyme-catalyzed hydrolytic reactions). Because the carbohydrate is on the molecule s surface, it may shield the polypeptide chain from proteolytic enzymes. 

Section 25 16 Carbohydrates and proteins that are connected by a chemical bond are called glycoproteins and often occur on the surfaces of cells They play an impor tant role m the recognition events connected with the immune response... 

Carbohydrates. The materials offered for fat replacement are either carbohydrate or protein and protein-like compounds (29). Table 3 fists carbohydrate fat-sparing agents. Another fisting is available (34) which includes materials offered on the European market. New compounds appear at such a rate that it is difficult to keep a current compilation proceedings from an aimual meeting are published (48). 

A wide variety of animal species are subjected to the administration of drugs during their lifetime.The various animal species can encounter drugs and other dietary additives by different routes and this is dependent on the environment in which they are kept. Intensively reared animals tend to have considerable consistency in the components of their diets and thus are much less likely to encounter the range of naturally produced compounds that extensively produced animals encounter. The desire for less expensive dietary constituents and increased efficiency of use has induced feed manufacturers and producers to add enzyme supplements to diets of most farmed animals to reduce the negative effects of indigestible dietary carbohydrates, refactory proteins and unavailable minerals such as phosphorus. This use of dietary additives to improve nutrient utilization and environmental consequences of feeding animals intensively has been the subject of intense research activity in the last five years. " The... 

Chemists and biochemists find it convenient to divide the principal organic substances present in cells into four main groups carbohydrates, proteins, nucleic acids, and lipids. Structural differences separate carbohydrates from proteins, and both of these are structurally distinct from nucleic acids. Lipids, on the other hand, are characterized by a physical property, their solubility in nonpolar solvents, rather than by their structure. In this chapter we have examined lipid molecules that share a common biosynthetic origin in that all their carbons are derived from acetic acid (acetate). The form in which acetate occurs in many of these processes is a thioester called acetyl coenzyme A. 

FIGURE 23.25 The effects of cortisol on carbohydrate and protein metabolism in the liver. 

Fig. 6.1 Schematic layout of food matrices suggested for a collaborative study based on protein (Prot), fat and carbohydrate (Cho) content, excluding moisture and ash...

The food, now in a liquid form known as chyme, passes through the pyloric sphincter into the duodenum, where stomach acid is neutralized. There is wide variation in lengths of the components of the small intestine (i.e., duodenum, jejunum, and ileum) between individuals (Table 98-1). Most absorption of digested carbohydrate and protein occurs within the jejunum. Most fat absorption occurs within the jejunum and ileum. In the small bowel, breakdown of macronutrients (i.e., carbohydrate, protein, and fat) occurs both within the lumen of the gut and at the intestinal mucosal membrane surface. The absorptive units on the intestinal mucosal membrane are infoldings known as... 

A considerable wealth of information is available on the general chemistry of these substances but precise structural knowledge is still lacking and a wide field of research awaits the activities of the chemist. This field not only covers carbohydrate and protein chemistry, but the area lying between the two, and it also borders on the lipid field. 

Such sugar-dendrimer complexes ( sugar balls ) have been used to inhibit the interactions of viruses with cell surfaces. Many viruses bind to particular carbohydrate residues on cell surfaces, which in turn facilitate their entry into cells and the resultant infection process. A virus particle presents a multi-dentate surface consisting of many carbohydrate-binding proteins able to interact with multiple cell-surface carbohydrates. The surface of a dendrimer that is modified with... 

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