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PubMed1987

Oxidation of phenylpyruvic acid.

Mn2+ catalyzes the aerobic oxidation of phenylpyruvic acid. Benzaldehyde and oxalate are the major products, the former being generated to some extent in an excited state, as indicated by chlorophyll-sensitized emission. Both oxygen consumption and emission are enhanced by addition of horseradish peroxidase. In the presence of the enzyme, halogen-containing xanthene dyes also sensitize the emission. From the values of the benzaldehyde/oxalate product ratio, it is inferred that two oxidation pathways are operative. One of these proceeds via a dioxetane intermediate and is responsible for the excited benzaldehyde; the other, which involves an alpha-keto-beta-peroxylactone, does not produce oxalate. The enzyme appears to favour the dioxetane route. The relative importance of these routes in biological systems is discussed.

Benzaldehydes↗
PubMed1993

Phenylpyruvic acid may be a direct precursor of mandelic acid without intermediate transamination of phenylalanine.

A series of compounds related to phenylalanine was administered to rats. Output of mandelic acid, a major but unexplained metabolite in phenylketonuria, was increased after the administration of phenylethanolamine or phenylpyruvic acid, whereas phenylethylamine or phenylalanine increased its excretion only marginally. Phenylacetic acid, previously suggested as a possible precursor in man, was almost without effect. It seems likely that mandelic acid can be formed from phenylpyruvic acid directly, without intermediate transamination to phenylalanine.

Animals↗
PubMed1981

Determination of phenylpyruvic acid in urine and serum by high-performance liquid chromatography with fluorescence detection.

A highly sensitive and simple method for the determination of phenylpyruvic acid in urine and serum is described which employs high-performance liquid chromatography with fluorescence detection. Phenylpyruvic acid, after extraction with ethyl acetate, is reacted with 4'-hydrazino-2-stilbazole in aqueous methanol to give the corresponding fluorescent hydrazone which is separated by reversed-phase chromatography on muBondapak Phenyl. The lower limits of detection are 25 and 32 pmol for phenylpyruvic acid in 0.2 ml of urine and serum, respectively. This sensitivity permits the determination of the acid in urine or normal adults and newborn infants.

Adult↗
PubMed1978

Improvement of the FeCl3 test for phenylpyruvic acid.

A simple alternative colorimetric method has been developed for quantitative determination of phenylpyruvic acid in urine based on the improved stability of the ferric complex of enol-phenylpyruvate in water-dimethylsulfoxide 50% vol. mixed solvent. The method can be applied directly to urine or to a dry ether-extract of urine. Operating on the dry ether-extract of urine, detection of phenylpyruvic acid is possible at an amount of as low as 1 mg/100 ml. Whereas, if urine samples are processed, detection is possible for a concentration of as low as 5 mg/100 ml and quantitative determination for a concentration greater than 10 mg/100 ml. The test carried out on a diaper wet with urine retains the same sensitivity and shows instantaneous development of the green colour.

Chlorides↗
PubMed1984

Clofibric acid, phenylpyruvate, and dichloroacetate inhibition of branched-chain alpha-ketoacid dehydrogenase kinase in vitro and in perfused rat heart.

Branched-chain alpha-ketoacid dehydrogenase kinase, purified from rabbit liver, was inhibited by clofibric acid, phenylpyruvate, and dichloroacetate in a mixed manner relative to ATP. I40 values relative to 75 microM ATP were 0.33, 1.7, and 3.0 mM, respectively. Inhibition of the kinase by acetate, pyruvate, and lactate was minimal; whereas a p-hydroxyphenyl substitution of these compounds increased their potency as kinase inhibitors, a phenyl substitution gave the most potent inhibitors. Clofibric acid, phenylpyruvate, and dichloroacetate activated branched-chain alpha-ketoacid dehydrogenase in perfused rat hearts. Perfusate concentrations that gave 50% activation (A50) were 0.1, 0.32, and 0.63 mM, respectively. A50 concentrations of clofibric acid and phenylpyruvate also increased flux (decarboxylation of alpha-keto[1-14C]isovalerate) through branched-chain alpha-ketoacid dehydrogenase in perfused rat heart. These findings suggest that, although clofibric acid and phenylpyruvate can inhibit substrate utilization by the branched-chain alpha-ketoacid dehydrogenase complex, the major effect of these compounds on branched-chain amino acid metabolism is due to inhibition of branched-chain alpha-ketoacid dehydrogenase kinase with subsequent activation of and increased flux through the complex.

Acetates↗
PubMedDate not supplied

Studies on phenylpyruvic acid. I. Keto-enol tautomerism.

The tautomerism of phenylpyruvic acid (PPA) and its sodium salt was investigated. The 1H and 13C spectra of PPA in aprotic solvents and in methanol show almost complete prevalence of the enol form, whereas the keto form prevails only in water. The Z configuration was assigned to the sole enol tautomer present on the basis of the value of the vicinal coupling constant [3J1H, 13COOH]=3.7 Hz. A small amount of the hydrated form of PPA (1-phenyl-2, 2-dihydroxylpropanoic acid) was found in the aqueous solution of its sodium salt and in buffer solution (pD=6) of PPA. By means of infrared spectroscopy one can conclude that crystalline PPA is in the enol whereas its sodium salt is in the keto form. The keto-acid was not obtained in the solid state. The colorimetric method for testing PPA traces in urine depends on the formation of a enol-Fe3+ complex (2:1) which appears stable in dimethylsulfoxide (DMSO).

Ferric Compounds↗
PubMed1999

[Studies on preparation of L-phenylalanine from phenylpyruvic acid by E. coli EP8-10].

E. coli EP8-10 was selected from the soil. It was able to produce the transaminase with high activity when it was cultivated on the medium containing peptone and beef extract. Optimum conditions of enzyme reaction was: phenylpyruvic acid's concentration of 0.3-0.5 mol/L, L-Asptaric acid used as amino donor, pH 8.5 37 degrees C. When phenylpyruvic acid was 0.3 mol/L, 48 g/L L-phenylalanine was produced after 6 h with 97% conversion rate.

Culture Media↗
PubMed1991

Cobalt(II)-catalyzed chemiluminescence in a dioctadecyldimethylammonium chloride bilayer membranous medium for the flow injection determination of phenylpyruvic acid.

A novel chemiluminescence system is described for the flow injection determination of phenylpyruvic acid (PPA). The presence of both ordered surfactant molecular assemblies and a metal ion catalyst in the system is essential for the phosphorescence of benzaldehyde (emitter) produced by the aerobic oxidation of PPA in alkaline solution. Dioctadecyldimethylammonium chloride bilayer aggregates and cobalt (II) allows PPA to be selectively determined down to 1 X 10(-7) M. The linearity is 2 orders of magnitude with a relative standard deviation 3.1% (n = 10) for 1 X 10(-6) M PPA. Of 28 other species (1 X 10(-3) M) tested, only 4-hydroxymanderic acid, 4-hydroxyphenylpyruvic acid, 2,5-dihydroxyphenylacetic acid, and 4-hydroxy-3-methoxyphenylpyruvic acid provided signals 2-13 times more intense than that for 1 X 10(-6) M PPA. PPA present at 10(-3) - 10(-2) M levels in urine from patients with phenylketonuria can be determined with no special sample pretreatment by using this CL procedure. The mechanistic study of the present luminescent reaction are also undertaken in detail. The bilayer aggregates were found to contribute favorably both to the production of key intermediates and to the efficient phosphorescence emission.

Adult↗
PubMed1976

High-speed liquid chromatographic determination of phenylpyruvic acid.

A high-speed liquid chromatographic method has been developed for the determination of urinary phenylpyruvic acid. This acid is converted by treatment with naphthalene-2,3-diamine into 3-benzyl-2-hydroxybenzoquinoxaline, which is extracted into carbon tetrachloride for separation. 2-Mercaptoethanol is a useful stabilizer, and 2-chlorothioxanthone is a suitable internal standard. The method is specific, and the results are not affected by the presence of such 2-oxo-acids as pyruvic acid, 2-oxobutyric acid, 2-oxoglutaric acid, and 4-hydroxphenylpyruvic acid.

Chemical Phenomena↗
PubMed1978

Quantitative analysis of beta-phenylpyruvic acid by single ion monitoring. Evaluation of isomeric internal standards.

Quantitative single ion monitoring of beta-phenylpyruvic acid at high sensitivity is possible after derivatization first with omicron-phenylenediamine and then with a silylating reagent. The resulting o-trimethyl-silyl-quinoxalinol (O-TMS-Q) has previously been shown to be highly stable during storage and on chromatography. As an internal standard the isomeric omicron-methylphenylglyoxylic (omicron-toluylformic) acid is introduced. The mass spectra of both O-TMS-Q's are characterized by abundant [M]+. at m/e 308. The concept of "class specific metabolic profiling" is discussed in relation to quantitative gas chromatography--mass spectrometry detection of aliphatic and aromatic alpha-ketoacids.

Chromatography, Gas↗