On carbohydrates

One outstanding feature of enzymes is that many of them are highly specific. Those that act on carbohydrates are particularly so, the slightest change in the stereochemical configuration of the molecule being sufficient to make a particular enzyme incompatible and unable to elTect hydrolysis. 

Both alkanes and gas oil can be used as carbon and energy sources. Commercially, Candida tropicalis and Candida lipolytica have been used (35,36). The fermentation contains two immiscible Hquid phases (the alkane and the water) the semisoHd yeast and the gaseous air phase. In contrast to yeasts grown on carbohydrates, where maximum yields are 50%, yeasts grown on alkanes generally give yields of 95—105% based on the weight of the alkane. 

The characteristics of enzymes are their catalytic efficiency and their specificity. Enzymes increase the reaction velocities by factors of at least one million compared to the uncatalyzed reaction. Enzymes are highly specific, and consequendy a vast number exist. An enzyme usually catalyzes only one reaction involving only certain substrates. For instance, most enzymes acting on carbohydrates are so specific that even the slightest change in the stereochemical configuration is sufficient to make the enzyme incompatible and unable to effect hydrolysis. 

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

Walter Haworth and Paul Karrer (W. H.) investigations on carbohydrates, vitamin C and (P. K.) investigation of carotenoids, flavins, and vitamins A and B2... 

Compare a) the minimum OTR and b) heat evolution rate of a continuous fermentation system based on n-alkanes operating at a dilution rate of 0.2 h 1 and a biomass concentration of 13.5 kg m 3, to a similar system based on carbohydrate. You may need to look back a few pages to get the relevant information concerning carbohydrate utilisation (Section 4.7). 

Currently dtric add is still manufactured almost entirely using A. niger growing on carbohydrate substrates. Three types of fermentation process have been used ... 

Since the early 1970s a panel convened by the International Union of Pure and Applied Chemistry and the International Union of Biochemistry and Molecular Biology has been working to formulate recommendations for carbohydrate nomenclature that meet developing needs of research and electronic data handling, while retaining links to the established literature base on carbohydrates. The realization of these endeavors is presented here in the final document Nomenclature of Carbohydrates, which provides a definitive reference for current researchers, both in the text version and in the version accessible on the World Wide Web (http //www.chem.qmw.ac.uk/iupac/2carb/), where amendments and revisions are maintained. 

Nowadays, a strategic area of research is the development of polymers based on carbohydrates due to the worldwide focus on sustainable materials. Since the necessary multi-step synthesis of carbohydrate-based polymers is not economical for the production of commodity plastics, functionalization of synthetic polymers by carbohydrates has become a current subject of research. This aims to prepare new bioactive and biocompatible polymers capable of exerting a temporary therapeutic function. The large variety of methods of anchoring carbohydrates onto polymers as well as the current and potential applications of the functionalized polymers has been discussed recently in a critical review [171]. Of importance is that such modification renders not only functionality but also biodegradability to the synthetic polymers. 

TGN is an informal worldwide grouping of scientists who share an interest in carbohydrates. The site contains considerable information on carbohydrates and an extensive list of links to other sites dealing with sugar-containing molecules). 

LAYER P, RIZZA R A, ZINSMEISTER A R, CARLSON G L, DIMAGNO E P (1986) Effect of a purified amylase inhibitor on carbohydrate tolerance in normal subjects and patients with diabetes mellitus . Mayo Clin Proc. 61 442-7. 

WOLVER T M s, JENKINS D J A (1993) Effect of dietary fiber and foods on carbohydrate metabolism. Dietary Fiber in Nutrition. In Ed. Spiller G A, Boca Raton, FL CRC Press. 111-52. 

Monascus pigments have been used in Asian countries for centuries as food colorants and spices and in traditional medicine. These pigments are produced by the fungi of Monascus genus cultivated on carbohydrate-rich substrates such as rice, wheat, com, potatoes, and soybeans. Three species of Monascus identified are pilosus. 

Attack of the OH radical on carbohydrates of low molecular mass gives rise to a variety of products. Indeed, the reaction of radiolytically-generated OH radical with lower hexose sugars produces lower saccharides (for di- and higher saccharide species), uronic and aldonic acids, and 3-, 2- and 1-carbon aldehydic fragments, e.g. 

There have been several syntheses of P-D lactone that were based on carbohydrate-derived starting materials. The starting material used in Scheme 13.42 was prepared from a carbohydrate produced in earlier work.27 The relative stereochemistry at C(4)... 

Gopal, N. H., Venkataramanan, D., Effect of ethrel on carbohydrate fractions of Coffea arabica L. fruits, Turrialba. 27, 101, 1977. (CA87 97235n)... 

Eggleston, G. and Vercellotti, J.R. (eds) (2007) Industrial Applications of Enzymes on Carbohydrate-based Materials, ACS Symposium Series 6, Oxford University Press. 

Vanover, L. and Komuniecki, P.R. (1989) Effect of gas phase on carbohydrate metabolism of Ascaris suum larvae. Molecular Biochemical Parasitology 36, 29-40. 

Bacillus krzemieniewski(f). This soil bacillus forms thick, gelatinous capsules on carbohydrate media and yields a polysaccharide which on hydrolysis is stated to produce L-mannose.660 This claim is based upon the melting point of the isolated mannose phenylhydrazone and upon the rotation of the hydrolyzed reaction mixture. It requires further confirmation. 

Editor, Symposia Organizer, and Expert on Carbohydrate Nomenclature... 

Even if the main focus on the research activities were directed towards structural studies on carbohydrates of natural origin, the synthesis of model substances, deriva-tization of oligo- and poly-saccharides, oxidation, and reduction of carbohydrates, and identification of the products all were performed during this time. 

This section describes the basic chemical attributes of carbohydrate molecules. Principal sites of reactivity on carbohydrates are discussed with the aim of developing a rational approach to using them in modification and conjugation procedures. 

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