Glyoxylic acid cycle derivatives

Secondary products derived from intermediates of the tricarboxylic and glyoxylic acid cycles (D 5)... 

Secondary products derived from the acids of the tricarboxylic acid, and glyoxylic acid cycles are built in microorganisms, plants, and animals. 

A. The Measurement of Isotopes. B. The Synthesis and Degradation of Labeled Compounds (Including. Application to Metabolic Studies) Monosaccharides and Polysaccharides Citric -Acid Cycle Intermediates Glycolic, Glyoxylic and Oxalic Acids Purines and Pyrimidines Porphyrins Amino. Acids and Proteins Steroids Methylated Compounds and Derivatives Sulfur Compounds Fatty. Acids Phospholipids Coenzymes lodinatftd Compounds Intermediates of Photosynthesis 0 -Labeled Phosphorus Compound. . 

Many aroma compounds in fruits and plant materials are derived from lipid metabolism. Fatty acid biosynthesis and degradation and their connections with glycolysis, gluconeogenesis, TCA cycle, glyoxylate cycle and terpene metabolism have been described by Lynen (2) and Stumpf ( ). During fatty acid biosynthesis in the cytoplasm acetyl-CoA is transformed into malonyl-CoA. The de novo synthesis of palmitic acid by palmitoyl-ACP synthetase involves the sequential addition of C2-units by a series of reactions which have been well characterized. Palmitoyl-ACP is transformed into stearoyl-ACP and oleoyl-CoA in chloroplasts and plastides. During B-oxi-dation in mitochondria and microsomes the fatty acids are bound to CoASH. The B-oxidation pathway shows a similar reaction sequence compared to that of de novo synthesis. B-Oxidation and de novo synthesis possess differences in activation, coenzymes, enzymes and the intermediates (SM+)-3-hydroxyacyl-S-CoA (B-oxidation) and (R)-(-)-3-hydroxyacyl-ACP (de novo synthesis). The key enzyme for de novo synthesis (acetyl-CoA carboxylase) is inhibited by palmitoyl-S-CoA and plays an important role in fatty acid metabolism. 

The acetyl-CoA used in the glyoxylate cycle is derived from the breakdown of fatty acids (/3-oxidation, see Chapter 12). In organisms with the appropriate enzymes, glucose can be produced from two-carbon compounds such as ethanol and acetate. In plants the reactions are localized within lipid bodies, glyoxysomes, mitochondria, and the cytoplasm. 

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