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Isovaleric Pathway

Allyl isovalcrate is metabolized to isovaleric acid, which can conjugate with glycine, and allyl alcohol, which could then be further metabolized via two pathways to fonn either acrolein or glycidol, from which a variety of metabolites could result (lARC, 1985). [Pg.1242]

Figure 20.20 Pathways of branched-chain amino acid metabolism. A, B, C, D, E, and F indicate defects in valinemia, maple syrup urine disease, isovaleric acidemia, /3-hydroxyisovaleric aciduria, a-methyl-j3-hydroxybutyric aciduria, and methylmalonic aciduria, respectively. Figure 20.20 Pathways of branched-chain amino acid metabolism. A, B, C, D, E, and F indicate defects in valinemia, maple syrup urine disease, isovaleric acidemia, /3-hydroxyisovaleric aciduria, a-methyl-j3-hydroxybutyric aciduria, and methylmalonic aciduria, respectively.
Leucine is a branched chain-amino acid that is essential or required in the diet. Mitochondrial catabolism of excess leucine occurs by the pathway shown in Figure 20-3. The initial transamination step (removal of the amino group) is followed by a decarboxylation reaction to produce isovaleric acid. It is this decarboxylation of the a-keto analogs of the three... [Pg.220]

Plants and microorganisms are capable of the de novo synthesis ofpantothenic acid from oxo-isovalerate and aspartate, by the pathway shown in Figure 12.3 animals are reliant on a preformed source of pantothenic acid. [Pg.351]

Although there are strain specific variations, the principle higher alcohols involved in wine aroma ares 1-propanol, 2-methyl-l-propanol, 1-butanol, 2-phenylethanol, 2-methyl-l-butanol, 3-methyl-l-butanol, 1-hexanol, l-octanol(23). These are likely to be derived in part, from amino acids via the Erhlich pathway. Organic Acids present ares acetic, isobutyric, isovaleric, hexanoic, and decanoic(24). Aldehydes present ares acetaldehyde, isobutyraldehyde,... [Pg.332]

Dolichotheline.—Dolichotheline (202) is an unusual imidazole alkaloid produced by the cactus Dolichothele sphaerica along a pathway which involves condensation of histamine with isovaleric acid. Administration of isocaproic acid and 4(5)-aminomethylimidazole led to the production of the unnatural alkaloids (203) and (204), respectively. ... [Pg.48]

They are defects in the degradation pathways of leucine, isoleucine, and valine. These conditions are usually diagnosed by examining organic acids in urine with abnormal metabolites also notable on acylcamitine profile. Organic acidemias comprise a variety of disorders and include methylmalonic acidemia (MMA), propionic acidemia (PROP), isovaleric acidemia (IVA), glutaric acidemia type 1 (GA-1), 3-methylcrotonyl carboxylase deficiency (3-MCC), 3-methylglutaconic acidemia (3-MGA), and vitamin B12 uptake, transport, and synthesis defects. [Pg.188]

Scheme 12.51. A pathway for the formation of valine (Val, V) from isovaleric (2-methyl-butanoic) acid. Scheme 12.51. A pathway for the formation of valine (Val, V) from isovaleric (2-methyl-butanoic) acid.
More precise information on the pathway of leucine catabolism was obtained from studies on the formation of ketone bodies in liver slices incubated with and C Mabeled leucine and isovaleric acid. In these experiments it was found that leucine-3-C yielded acetoacetate in which the label was virtually all contained in the methyl and methylene carbons, and to approximately the same extent in each of these. Only a trace of radioactivity was found in the carboxyl carbon. On incubation with leucine-4-Ci the label occurred solely in the carbonyl group. This suggested that the isopropyl group of the amino acid had been directly converted to acetone. The over-all conclusion was that the isopropyl group forms acetone, and carbons 2 and 3 of the amino acid yield a 2-car-bon fragment which can condense to acetoacetate. The acetoacetate formed from leucine-4-C was not symmetrically labeled, the isotope being present only in the carbonyl carbon. [Pg.67]

The mechanism of fusel oil production from carbohydrates follows the typical Embden-Meyerhof-Pamas pathway to pyruvic acid. Pyruvic acid may be reacted with a second pyruvic acid to yield acetolactic acid. Acetolactic acid enters the valine-isoleucine biosynthesis pathway and is converted to a-keto isovaleric acid. The a-keto isovaleric acid may then be reduced to isobutyl alcohol or isobutyric... [Pg.127]

Additional evidence for the pathway of catabolism of leucine was obtained from a study of the degradation of isotopically-labeled isovaleric acid. This is considered to be an obligatory intermediate as is shown in reaction 2 of Fig. 6. [Pg.104]

Fujii et al. (1988) reported a mechanism of isobutene formation by the yeast Rhodotorula minuta in a culture medium that contained branched-chain carboxylic or amino acids. It was suggested that the pathway leads over isovalerate that is decarboxylated to isobutene. [Pg.112]

Later, it was concluded that isobutene was synthesised through decarboxylation of isovalerate that is produced in the catabolic pathway of L-leucine (Fukuda et al. 1985, 1994). The decarboxylation reaction is catalysed by a microsomal cytochrome P450 (cytochrome P450rm) in the presence of NADPH, O2 and cytochrome P450, which was an NADPH reductase (Fujii et al. 1988 Fukuda et al. 1994). The initial (and also the rate limiting) step of this reaction is the removal of the hydrogen atom at the p-carbon atom of isovalerate, which is then followed by decarboxylation. P450rm accepts electrons from the reductase and catalyses the formation of isobutene from isovalerate (Fukuda et al. 1994). [Pg.138]

The isobutene metabolic pathway goes along the leucine biosynthesis pathway, from glucose to 2-ketoisocaproate (4-methyl-2-keto-pentanoate). The next two steps lead to isovalerate with a CO2 unit splitting off, which is then transformed to isobutene with cytochrome P450 as catalyst and additional CO2 equivalent separating (van Leeuwen et al. 2012). [Pg.139]

Theoretically, it should be possible to reach 3-hydroxyisovalerate over 2-hydroxyisovalerate. This approach would use only 2 mol of acetyl-CoA per mol of isobutene and use the MDD decarboxylation into isobutene. First, part of this pathway would be similar to the pathways via isovalerate and isobutanol. The reduction of 2-oxoisovalerate to l- or D-2-hydroxyisovalerate requires D-lactate dehydrogenase (van Leeuwen et al. 2012 Chambellon et al. 2009). [Pg.143]

The oxidation of heptane and hexane by a strain of Pseudomonas aeruginosa was found to occur by oxidative attack of one terminal carbon atom, yielding the corresponding fatty acids, which were further degraded by j8-oxidation (Heringa et al., 1961). Evidence for a decarboxylation of the fatty acids could not be found. Two pathways of oxidation of 2-methylhexane were found. The main attack occurs in the C-6 yielding 5-methylhexanoic acid and, via /3-oxidation, isovaleric acid. The second, minor pathway involves attack of the other end of the hydrocarbon molecule, namely, the C-1, yielding 2-methylhexanoic acid (Thijsse and van der Linden, 1961). [Pg.268]


See other pages where Isovaleric Pathway is mentioned: [Pg.669]    [Pg.171]    [Pg.123]    [Pg.484]    [Pg.34]    [Pg.226]    [Pg.289]    [Pg.190]    [Pg.856]    [Pg.58]    [Pg.67]    [Pg.187]    [Pg.377]    [Pg.359]    [Pg.177]    [Pg.428]    [Pg.164]   
See also in sourсe #XX -- [ Pg.58 ]




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