Complex carbohydrates, biosynthesis plants

LIPID-LINKED SUGARS AS INTERMEDIATES IN THE BIOSYNTHESIS OF COMPLEX CARBOHYDRATES IN PLANTS... 

Lipid-linked sugars as intermediates in the biosynthesis of complex carbohydrates in plants, R. Pont Lezica, G. R. Dalev, and R. M. Dey, Adv. Carbohydr. Chem. Biochem., 44(1986) 341-386. 

Elbein, A.D. (1979). The Role of Lipid Linked Saccharides in the Biosynthesis of Complex Carbohydrates . Annual Reviews of Plant Physiology, 30, 239-272. 

ABSTRACT This article describes recent developments in the chemistry of an important family of complex monosaccharides which have diverse structures and participate in a wide range of biological processes. For example 3-deoxy-D-/n nno-2-octulosonic acid (KDO) is a key component of the lipopolysaccharides (LPS) of Grammnegative bacteria, 3-deoxy-D-araftmo-2-heptulosonic acid (DAH) is a key intermediate in the biosynthesis of aromatic amino acids in bacteria and plants. A number of their syntheses that were achieved by homologation reactions of the natural carbohydrate units using enzymatic or chemical methods, as well as by total synthetic approaches are here included. Special emphasis is placed on new methodologies and their correlation with the biosynthetic pathway of the corresponding ulosonic acids. 

The citric acid cycle, also known as the tricarboxylic acid cycle or the Krebs cycle, is the final oxidative pathway for carbohydrates, lipids, and amino acids. It is also a source of precursors for biosynthesis. The authors begin Chapter 17 with a detailed discussion of the reaction mechanisms of the pyruvate dehydrogenase complex, followed by a description of the reactions of the citric acid cycle. This description includes details of mechanism and stereospecificity of some of the reactions, and homologies of the enzymes to other proteins. In the following sections, they describe the stoichiometry of the pathway including the energy yield (ATP and GTP) and then describe control mechanisms. They conclude the chapter with a summary of the biosynthetic roles of the citric acid cycle and its relationship to the glyoxylate cycle found in bacteria and plants. 

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