Carbohydrates, biological synthesis, with

The present position with regard to the biological synthesis and interconversion of monosaccharides has been reviewed by L. Hough and J. K. N. Jones, Advances in Carbohydrate Chem., 11, 185 (1956). 

When the source of plant raw material for humus synthesis is cut off, such as when eroded soil is transported to sediments, humus is exposed to successive cycles of biological attack, with concomitant changes in chemical composition. Easily decomposable compounds, such as proteins and carbohydrates, are attacked first, with the result that these constituents are eliminated at the expense of resistant molecules such as humic and fulvic acids. 

There have been several recent solid-phase and solution-phase libraries reported that contain the spiroketal moiety (Figure 7.5). These libraries introduce additional structural complexity and new interaction modes of carbohydrate-like molecules with biological targets. Ley and cowoikers reported the solid-supported synthesis of spiroketals. Using stereoselective aldol reactions of boron enolates, the Waldmann and Paterson groups reported the solid-phase synthesis of 6,6-spiioketals. The 1,7-dioxaspiro [5.5]undecane spiroketal served as the core template for Porco s three-point diversity library to explore protein-protein interactions. ... 

Chabre YM, Roy R (2011) Solving promiscuous protein carbohydrate recognition domains with multivalent glycofullerenes. In Renaudet O, Spinelli N (eds) Synthesis and biological applications of glycoconjugates. Bentham Science, Oak Park, pp. 64—77... 

Other evidence that a carbohydrate is the precursor of the main carbon chain of histidine has been secured with Neurospora. Certain histidine-requiring mutants of this organism have been observed to accumulate imidazole derivatives in the incubation medium that are related in some way to the biological synthesis of histidine. None of the accumulated imidazoles, however, could support the growth of any of the Neurospora mutants. Three of this class of compounds have been isolated from Neurospora mutants and a fourth (IV) from two mutant strains of Penicillium. Their structural formulas and names are showai below. 

In the area of synthesis Garegg has surveyed various regioselective reactions which are applied in oligosaccharide synthesis under the title "Challenges and opportunities for organic synthesis with saccharides of biological importance." More specifically a substantial review has dealt with basic aspects of the major issue of the methods available for the preparation of 1,2-asymmetric centres with defined relative stereochemistry, and 1,3-difunctional compounds in which 1,2-difunctional stereorelationships may also be established. A later publication which builds on this will be of more specific relevance in carbohydrate chemistry. More specific topics to have been surveyed are cycloaddition reactions in carbohydrate chemistry and noble metal-catalysed oxidations of carbohydrates. ... 

Triiodothyronine (3, 5,3-L-triiodothyronine, T3) is a thyroid hormone. It is producedby outer ring deiodination of thyroxine (T4) in peripheral tissues. The biologic activity of T3 is 3-8 times higher than that of T4. T3 is 99.7% protein-bound and is effective in its free non-protein-bound form. The half-life of triiodothyronine is about 19 h. The daily tur nover of T3 is 75%. Triiodothyronine acts via nuclear receptor binding with subsequent induction of protein synthesis. Effects of thyroid hormones are apparent in almost all organ systems. They include effects on the basal metabolic rate and the metabolisms of proteins, lipids and carbohydrates. 

Kojic acid, 5-hydroxy-2-(hydroxymethyl)-4//-pyran-4-one1 (II), is produced from carbohydrate sources in an aerobic process by a variety of microorganisms. The acid was discovered in 1907, its structure was established in 1924, and its chemical synthesis from D-glucose was achieved in 1930. Since then, a considerable amount of study has been devoted to the biosynthesis of kojic acid, and numerous publications have dealt with its chemical and biological properties. After nearly half a century, kojic acid remains a scientists curiosity, without industrial importance. It con-... 

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