Carbohydrates mechanisms

Comparative adhesion of B16 cells based on integrin-dependent, lectin-dependent, and carbohydrate-carbohydrate mechanisms, under dynamic flow conditions, is illustrated schematically in Figure 5. At certain shear stress values, carbohydrate-based adhesion is much stronger than integrin-dependent adhesion. 

CHEAT (carbohydrate hydroxyls represented by external atoms) a molecular mechanics force field... 

Biochemistry resulted from the early elucidation of the pathway of enzymatic conversion of glucose to ethanol by yeasts and its relation to carbohydrate metaboHsm in animals. The word enzyme means "in yeast," and the earfler word ferment has an obvious connection. Partly because of the importance of wine and related products and partly because yeasts are relatively easily studied, yeasts and fermentation were important in early scientific development and stiU figure widely in studies of biochemical mechanisms, genetic control, cell characteristics, etc. Fermentation yeast was the first eukaryote to have its genome elucidated. 

The principal steps in the mechanism of polyisoprene formation in plants are known and should help to improve the natural production of hydrocarbons. Mevalonic acid, a key intermediate derived from plant carbohydrate via acetylcoen2yme A, is transformed into isopentenyl pyrophosphate (IPP) via phosphorylation, dehydration, and decarboxylation (see Alkaloids). IPP then rearranges to dimethylaHyl pyrophosphate (DMAPP). DMAPP and... 

Somatotropin, the P-adrenergic agonists, and the anaboHc steroids are considered metaboHsm modifiers because these compounds alter protein, Hpid, carbohydrate, mineral metaboHsm, or combinations of these and they partition nutrient use toward greater rates of protein deposition, ie, muscle growth, and lesser rates of Hpid accretion. Historical data leading to understanding of the mechanism (s) of action are found in reviews on anaboHc steroids (1), somatotropin (2—4), and the phenethano1 amines (5—7). 

An alternative view (123) is that no single model can adequately explain why any given compound is sweet. This hypothesis derives from several features. First, there is the observation that all carbohydrates having a critical ratio of OH to C are sweet tasting. In other words, there are no stmctural constraints to the sweetness of carbohydrates. Second, not all sweeteners can be fit to the same SAR model. Rather, some fit one, others fit another. Third, studies on the transduction mechanisms of sweetness suggest more than a single mechanism for sweet taste, implying multiple receptors for sweeteners. 

Recently, Li et al. [30], Yu et al. [31] reinvestigated the mechanism of graft copolymerization of vinyl monomers onto carbohydrates such as starch and cellulose initiated by the Ce(IV) ion with some new results as mentioned in Section II. Furthermore, they investigated the mechanism of model graft copolymerization of vinyl monomers onto chitosan [51]. They chose the compounds containing adjacent hydroxyl-amine structures, such as D-glucosamine, /mn5-2-amino-cyclohexanol, 2-... 

It would be reasonable to expect that the decomposition of the N,N-dimethylimino ester chlorides proceeds via a bimolecular mechanism already demonstrated for the thermal decomposition of simple imino ester salts (79). In the carbohydrate series, where an isolated secondary hydroxyl group is involved, such a process would result in chlorodeoxy sugar derivatives with overall inversion of configuration, provided that the approach of the chloride ion is not sterically hindered. Further experiments are in progress in this laboratory utilizing additional model substance to establish the scope and stereochemical course of the chlorination reaction. 

One of the steps in the biological pathway for carbohydrate metabolism is the conversion of fructose 1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. Propose a mechanism for the transformation. 

Design your own degradative pathway. You know the rules (organic mechanisms), and you ve seen the kinds of reactions that occur in the biological degradation of fats and carbohydrates inLo acetyl CoA. If you were Mother Nature, what series of steps would you use to degrade the amino acid serine into acetyl CoA ... 

Williamson, Alexander W., 655 Williamson ether synthesis, 655 carbohydrates and, 988 mechanism of, 655... 

The tiiyroid hormones influence every organ and tissue of tiie body. These hormones are principally concerned with increasing tiie metabolic rate of tissues, which results in increases in tiie heart and respiratory rate, body temperature, cardiac output, oxygen consumption, and the metabolism of fats, proteins, and carbohydrates. The exact mechanisms by which tiie tiiyroid hormones exert their influence 011 body organs and tissues are not well understood. 

Because sugars are involved in most of the mechanisms established for the synthesis of these heterocycles, the development of carbohydrate chemistry has been most helpful in these researches—especially for the preparation of specifically labeled molecules. Conversely, the contribution of these efforts to carbohydrate chemistry and biochemistry has shown the involvement in biosynthesis of 1 -deoxy-D-f/rreo-pentulose—scarcely before recognized and considered a rare sugar—and of fully functionalized pentuloses of still unknown configuration (or their phosphates). Finally, evidence has been found in prokaryotes for a most extraordinary transformation of 5-amino-l-(P-D-ribofuranosyl)imidazole 5 -phos-phate into a pyrimidine. Surely, this transformation should be explained in terms... 

Carbohydrate feeding during prolonged exercise can delay fatigue. J. Appl. Physiol. 55,230-235. Edwards, R.H.T. (1981). Human muscle function and fatigue. In Human Muscle Fatigue Physiological Mechanisms (Porter, R. Whelan, J., eds.), pp. 1—18, Pitman, London. 

---