Carbohydrates, enzymic synthesis

Ghanges in the availability of substrates are responsible for most changes in metabolism either directly or indirectly acting via changes in hormone secretion. Three mechanisms are responsible for regulating the activity of enzymes in carbohydrate metabolism (1) changes in the rate of enzyme synthesis, (2) covalent modification by reversible phosphorylation, and (3) allosteric effects. 

One of the recent fundamental advances in carbohydrate chemistry has been enzymic synthesis in vtiro this has now been realized with dextran8 and with levan.8 However, since phosphate sugars are not involved in the enzymic syntheses of these two bacterial polysaccharides, it is obvious that phosphorylation is just one process for the natural synthesis of polysaccharides. 

N. Asano, K. Oseki, E. Kaneko, and K. Matsui, Enzymic synthesis of a- and p-D-glucosides of 1-deoxynojirimycin and their glycosidase inhibitory activities, Carbohydr. Res., 258 (1994) 255-266. 

The liver is involved in a variety of both synthetic and catabolic functions, including metabolism of amino acids, lipids, carbohydrates, protein synthesis and detoxification [ 1 ]. These metabolic functions are performed mainly by hepatocytes, although the liver is made of three major cell types (hepatocytes, biliary epithelial cells and Kupffer cells). Exerting many different metabolic functions, the liver contains several different and specific enzymes, leakage of which into the bloodstream occurs in hepatic diseases. 

A large-scale enzymic synthesis of the trisaccharide a-D-Neu5Ac-(2—>3)-j8-D-Gal-( 1 — 3)-d-G1cNAc (65), the tumor-associated carbohydrate antigen CA 50, has been achieved.113 This is a further illustration of the cross reactivity and efficiency of STB, This sialyltransferase, like STA, was partially purified from porcine liver, according to a modification of Conradt s procedure. 114 The initial rate measured for j8-d-Gal-( 1 - 3)-d-G1cNAc at saturating concentration was 18% of the one measured for the real substrate / -d-... 

Kopper S, Polymer-supported enzymic synthesis on a preparative scale, Carbohydrate Research, 265 161-66, 1994. 

Wiemann T, Taubken N, Zehavi U, Thien J, Enzymic synthesis of N-acetyllactosamine on a soluble, light-sensitive polymer, Carbohydr. Res., 257 C1-C6, 1994. 

Zehavi U, Herchman M, Enzymic synthesis of oligosaccharides on a polymer support, light-sensitive, water-soluble substituted poly(vinyl alcohol), Carbohydr. Res., 128 160-164, 1984. 

Svensson SCT, Thiem J. Purification of a-fucosidase by C-glycosylic affinity chromatography, and the enzymic synthesis of a-fucosyl disaccharides Carbohydr. Res. 1990 200 391-402. 

Long-term High-carbohydrate, low-fai diet enzyme synthesis... 

Fatty acid synthase H h-carbohydrate, low-fat diet t enzyme synthesis... 

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