Dicarboxylic acids methyl branched

Very-long-chain fatty acids as erucic acid (A -docosenoic acid, C22 l), polyunsaturated fatty acids, methyl-branched fatty acids, dicarboxylic fatty acids, prostaglandins, and the cholesterol side chain in bile acid synthesis are preferentially or exclusively oxidised in peroxisomes. Peroxisomal P-oxidation starts with introduction of a A2,3-double bond catalysed by acyl-CoA oxidase, which consumes O2 and produces H2O2 (Foerster et al. 1981). 

G-20 Dicarboxylic Acids. These acids have been prepared from cyclohexanone via conversion to cyclohexanone peroxide foUowed by decomposition by ferrous ions in the presence of butadiene (84—87). Okamura Oil Mill (Japan) produces a series of commercial acids based on a modification of this reaction. For example, Okamura s modifications of the reaction results in the foUowing composition of the reaction product C-16 (Linear) 4—9%, C-16 (branched) 2—4%, C-20 (linear) 35—52%, and C-20 (branched) 30—40%. Unsaturated methyl esters are first formed that are hydrogenated and then hydrolyzed to obtain the mixed acids. Relatively pure fractions of C-16 and C-20, both linear and branched, are obtained after... 

Although the mitochondria are the primary site of oxidation for dietary and storage fats, the peroxisomal oxidation pathway is responsible for the oxidation of very long-chain fatty acids, jS-methyl branched fatty acids, and bile acid precursors. The peroxisomal pathway also plays a role in the oxidation of dicarboxylic acids. In addition, it plays a role in isoprenoid biosynthesis and amino acid metabolism. Peroxisomes are also involved in bile acid biosynthesis, a part of plasmalogen synthesis and glyoxylate transamination. Furthermore, the literature indicates that peroxisomes participate in cholesterol biosynthesis, hydrogen peroxide-based cellular respiration, purine, fatty acid, long-chain... 

Mortensen, P.B., Gregersen, N., Kolvraa, S. Christensen, E. (19W) Biochem. Med 24, 1531-1561. The occurrence of C6-C10-dicarboxylic acids in urine from patients and rats treated with dipropylacetate. Ikeda, Y, Dabrowsly, C. Tanaka, K. (1983) J. Biol. Chem. 258, 1066-1076. Separation and properties of five distinct acyl-CoA dehydrogenases from rat liver mitochondria. Identification of a new 2-methyl branched chain acyl-CoA dehydrogenase. 

Bbcin the monomethyl ester of the C24 dicarboxylic acid, norbixin. Norbixin has 4 methyl side branches, 2 terminal carboxyl groups and 9 conjugated double bonds. Ihe C20 chain corresponds to the middle part of P-carotene. In naturally occurring B. (m.p. 198 C) the A double bond is cis, but it easily isomerlzes to form the more stable all-trans B. (m. p. 217 °C). B. is a diapocarotenoid formed by oxidation of a C40 carotenoid. It is a yellow to red-orange pigment found in the seeds of Bixa orellana, from which it is extracted for use as a food colorant. 

Crocetin a brick-red Cjo dicarboxylic acid, M, 328.39, m.p. 285 C, with 7 conjugated irons double bonds, 4 methyl branches and 2 terminal carboxyl groups. It is a carotenoid oxidation product or apocar-... 

Sugars Unusual sugars (amino, deoxy and methyl sugars, and sugars with branched chains). Reduction products (sugar alcohols, cyclitols, streptidine). Oxidation products (uronic acids, aldonic acids, sugar dicarboxylic acids). 

Witten et al. (1973) identified adipic and 3-methyladipic acids and also reported the presence in urine, using GC-MS, of aconitic and isocitric acids in addition to citrate. Mamer et al, (1971) reported the occurrence of several hydroxyaliphatic acids in addition to those already identified by other workers, and Mamer and Tjoa have identified 2-ethylhydracrylic acid in urine derived from isoleucine metabolism (Mamer and Tjoa, 1974). Urine from healthy children and adults may contain low amounts of aliphatic dicarboxylic acids of chain length C4-C8 (Lawson et ai, 1976). Pettersen and Stokke (1973) reported a series of 3-methyl-branched C4-C8 dicarboxylic acids in urine from normal subjects, and Lindstedt and co-workers have identified other dicarboxylic acids with cyclopropane rings and acetylenic bonds as well as a series of cis and trans mono-unsaturated aliphatic dicarboxylic acids (Lindstedt et al., 1974,1976 Lindstedt and Steen, 1975). 

This chapter describes the case reports of these enzyme deficiencies and the underlying biochemistry of the disorders and their associations. It is not the intention to discuss keto acidosis associated with other diseases, for example juvenile diabetes, or ketogenesis and its control which are reviewed elsewhere (Wildenhoff, 1975, 1977 McGarry and Foster, 1976 Halperin, 1977). In addition to the common occurrence of 3-hydroxybutyrate and acetoacetate in body fluids of patients with keto acidosis, secondary organic acids have been observed in urine, including adipic and suberic acids (Pettersen et aL, 1972), 3-hydroxyisovaleric acid (Landaas, 1974), 3-hydroxyisobutyric acid and 2-methyl-3-hydroxybutyric acid (Landaas, 1975). The dicarboxylic acids occur as a result of initial co-oxidation of accumulating long-chain fatty acids followed by )8-oxidation (Pettersen, 1972), and metabolites of the branched-chain amino acids occur because of inhibition of their metabolic pathways by 3-hydroxybutyrate and acetoacetate (Landaas and Jakobs, 1977). 

The main route of energy provision from fatty acids is the 3-oxidation pathway in which carbon atom C-3 (p-carbon) is oxidized. In man, other pathways also exist. The a-oxidation pathway which involves the oxidation of the C-2 atom is important in the degradation of ingested branched fatty acids and brain lipids to prepare such fatty acids for entry into the P-oxidation route. The ca (omega)-pathway involves the oxidation of the terminal methyl group primarily of to C, fatty acids. The dicarboxylate product enters the p-oxidation pathway. 

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