Metabolism organic acids

Figure 9 Proposed role of organic acid metabolism (citrate) in genotypical differences of rice in adaptation to high levels of soil bicarbonate tmd low Zn availability. (Adapted t rora Ref. 233.)...

Protein synthesis and changes in lipid and organic acid metabolism ... 

The reported (14) mechanisms of action of allelochemlcals Include effects on root ultrastructure and subsequent Inhibition of Ion absorption and water uptake, effects on hormone-induced growth, alteration of membrane permeability, changes In lipid and organic acid metabolism, inhibition of protein synthesis and alteration of enzyme activity, and effects on stomatal opening and on photosynthesis. Reduced leaf water potential Is one result of treatment with ferulic and p-coumaric acids (15). Colton and Einhellig (16) found that aqueous extracts of velvetleaf (Abutllon theophrastl Medic.) Increased diffusive resistance In soybean fGlycine max. (L.) Merr.] leaves, probably as a result of stomatal closure. In addition, there was evidence of water stress and reduced quantities of chlorophyll In Inhibited plants. 

This in fact is what happened. Tandem MS has clearly been shown to be the only technology to screen for disorders of fatty acid oxidation and could also detect many disorders of organic acid metabolism. Tandem MS has the ability to detect both compound classes (amino acids and acylcarnitines) and after demonstrating that both classes could be prepared in the same manner, the MS/MS analysis of blood spots for newborn screening applications was born. 

Table 3.1.1 Disorders of organic acid metabolism (in alphabetical order). This table does not include disorders with primary accumulation of amino acids, disorders of mitochondrial fatty acid oxidation, or primary lactic acidemias. Co A Coenzyme A, FAD flavin adenine dinucleotide...

Chalmers RA, Roe CR, Stacey , Hoppel CL (1988) Urinary excretion of L-carnitine and acylcarnitines by patients with disorders of organic acid metabolism evidence for secondary insufficiency of L-carnitine. Pediatr Res 18 1325-1328... 

Growth substances evidently affect protein synthesis and bring changes in lipids and organic acid metabolism. Undoubtedly, this is a fruitful area for future research. 

Interpretation of complex metabolic profiles and communication of lab results to clinicians has been one of the greatest challenges in dried blood spot analysis by MS/MS for acylcamitines and amino acids. Following its introduction, MS/MS defined numerous diseases of fatty acid and organic acid metabolism that were uncommonly encountered in a typical practice and not well understood by most pediatricians. Furthermore, even in disorders such as PKU that were well known, the improvements made by MS/MS screening for PKU compared with older technology such as BIA or fluorometry were not well... 

Regarding organic acids metabolism, Amati et al. (1983) reported that malic acid is consumed in both natural and conditioned systems, although it was more intense in the latter. This malic acid decrease is probably due to the respiration processes and /or to malic acid conversion into sugar (gluconeogenesis). In contrast, tartaric acid decreases slightly, and no differences were seen between the two drying systems. 

TABLE 55-f Typical Outcorne of Rout Organic Acid Metabolism... 

Table 55-3 shows a summary of known disorders of organic acid metabolism, including information about their incidence, major clinical features and biochemical patterns, availability of prenatal diagnosis and newborn screening, and association with sudden unexpected death. The incidence of individual inborn errors of organic add metabolism varies from 1 10,000 to >1 1,000,000 live births. All possible disease entities included, the incidence of conditions in which informative organic acid profiles could be detected in urine is likely to approach 1 1000 live births. 

Several selected disorders of organic acid metabolism are discussed below. 

Propionyl-CoA is an intermediary product in the metabo-hsm of four essential amino acids (isoleucine, valine, threonine, and methionine), the aliphatic side-chain of cholesterol, pyrimidines (uracd and thymine), and the final product of the [3-oxidation of odd-chain fatty acids. Under normal circumstances, propionyl-CoA first is converted by a biotin-dependent carboxylase to methylmalonyi-CoA, then to succinyl-CoA by an adenosylcobalamin-dependent mutase, leading to oxidation in the tricarboxylic acid cycle. Primary or secondary defects of these two enzymes were among the first organic acidurias to be discovered, and their natural history has been characterized perhaps better than any other inborn error of organic acid metabolism. 

TAB1 E and Laboratory Characteristics of Disorders of Organic Acid Metabolism —Continue ... 

Photo synthetic Nitrogen Assimilation and Associated Organic Acid Metabolism (Editors C. H. Foyer and G. Noctor) ... 

Whiting, G.C. Coggins, P.A. 1960. Organic acid metabolism in cider and perry fermentations. III. Keto-acids in cider-apple juices and ciders. J Sci Food Agric. 11 705-709. 

Kyhal, J., Svohoda, E., Strnadova, K. and Kejzlar, M. (1981) Role of organic acid metabolism in the biosynthesis of peptide ergot alkaloids. Folia Microbiol., 26, 112-119. 

Chronic, recurrent) pancreatitis Hepatosplenomegaly Reye or "Reye-like syndromes Recurrent severe infections (Non-immune hemolytic) anemia Myeloproliferative syndrome (Cave Routine chemical abnormalities such as hypoglycemia, metabolic acidosis, lactic acidosis, hyperammonemia or ketonuria, the usual concomitants of disorders of organic acid metabolism, can be conspicuously absent in the last two categories)... 

Hoffmann GF, Gibson KM (1996) Disorders of organic acid metabolism. In Moser HW (ed) Handbook of Clinical Neurology Neurodystrophies and Neurolipidoses, Vol. 66, Elsevier Science Publishers, Amsterdam, pp 639-660... 

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