Liver-L-alanine-glyoxylate and L-serine-pyruvate aminotransferase activities: an apparent association with gluconeogenesis

Rowsell, E. V.; Snell, Keith; Carnie, John; al-Tai, A H

doi:10.1042/bj1151071

Cited by 94 publications

(57 citation statements)

References 14 publications

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“…Standard methods were used to assay 1-aminopropan-2-ol-O-phosphate phospholyase (Faulkner & Turner, 1974), glycine-pyruvate aminotransferase (Rowsell et al, 1969), glyoxylate carbo-ligase (Kornberg & Gotto, 1961) and erythro-,8-hydroxyaspartatedehydratase (Kornberg & Morris, 1965).…”

Section: Enzyme Assaysmentioning

confidence: 99%

Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine-NAD+ oxidoreductase

Bell

Turner

1976

Biochemical Journal

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1. Isolates representing seven bacterial genera capable of growth on L-threonine medium, and possessing high L-threonine 3-dehydrogenase activity, were examined to elucidate the catabolic route. 2. The results of growth, manometric and enzymic experiments inddicated the catabolism of L-threonine by cleavage to acetyl-CoA plus glycine, the glycine being further metabolized via L-serine to pyruvate, in all cases. No evidence was obtained of a role for aminoacetone in threonine catabolismn or for the metabolism of glycine by the glycerate pathway. 3. 'Te properties of a number of key enzymes in Lthreonine catabolism were investigated. The inducibly formed L-threonine 3-dehydrogenase, purified from Corynebacterium sp. B6 to a specific activity of about 30-354umol of product formed/min per mg of protein, exhibited a sigmoid kinetic response to substrate concentration. The half-saturating concentration of substrate, [S]0.S, was 20mM and the Hill constant (h) Wvas 1.5. The Km for NAD+ was 0.8 mm. The properties ofthe enzyme were studied in cell-free extracts of other bacteria. 4. New assays for 2-amino-3-oxobutyrate-CoA ligase were devised. The Km for CoA was determined for the first time and found to be 0.14nmm at pH8, for the enzyme from Corynebacteriumf sp. B6. Evidence was obtained for the efficient linkage of the dehydrogenase and ligase enzymes. Cell-free extracts all possessed high activities of the inducibly formed ligase. 5. L-Serine hydroxymethyltransferase was formed constitutively by all isolates, whereas formation of the 'glycine-cleavage system' was generally induced by growth on L-threonine or glycine. The coenzyme requirements ofboth enzymes were established, and their linked activity in the production of L-serine from glycine was demonstrated by using extracts of Corynebacterium sp. B6. 6. L-Sernne dehydratase, purified from Corynebacterium sp. B6 to a specific activity of about 4pmol of product formed/min per mg of protein, was found to exhibit sigmoid kinetics with an [S]0.S of about 20mM and h = 1.4. Similar results were obtained with enzyme preparations from all isolates. The enzyme required Mg2+ for maximum activity, was different from the L-threonine dehydratase also detectable in extracts, and was induced by growth oh t-threonine or glycine.

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Section: Enzyme Assaysmentioning

confidence: 99%

Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine-NAD+ oxidoreductase

Bell

Turner

1976

Biochemical Journal

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“…Another potential de novo pathway, referred to as the non-phosphorylated pathway, starts with a glycolytic intermediate 2-phosphoglycerate (3). In liver, the non-phosphorylated pathway is presumed to operate mainly in the reverse direction for gluconeogenesis (4). Glycine also can be converted directly into L-serine by serine hydroxymethyltransferase, with N 5 ,N 10 -methylenetetrahydrofolate acting as a carbon donor (5).…”

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confidence: 99%

Targeted Disruption of the Mouse 3-Phosphoglycerate Dehydrogenase Gene Causes Severe Neurodevelopmental Defects and Results in Embryonic Lethality

Yoshida

Furuya²,

Osuka³

et al. 2004

Journal of Biological Chemistry

132

107

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D-3-Phosphoglyceratedehydrogenase (Phgdh; EC 1.1.1.95) is the first committed enzyme of L-serine biosynthesis in the phosphorylated pathway. To determine the physiological importance of Phgdh-dependent L-serine biosynthesis in vivo, we generated Phgdh-deficient mice using targeted gene disruption in embryonic stem cells. The absence of Phgdh led to a drastic reduction of Lserine metabolites such as phosphatidyl-L-serine and sphingolipids. Phgdh null embryos have small bodies with abnormalities in selected tissues and died after days post-coitum 13.5. Striking abnormalities were evident in the central nervous system in which the Phgdh null mutation culminated in hypoplasia of the telencephalon, diencephalon, and mesencephalon; in particular, the olfactory bulbs, ganglionic eminence, and cerebellum appeared as indistinct structures. These observations demonstrate that the Phgdh-dependent phosphorylated pathway is essential for normal embryonic development, especially for brain morphogenesis.

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“…Clycine-pyruvate aminotransferase was assayed spectrophotometrically by assaying the rate of oxidation of NADH by a coupled spectrophotometric method using exogenous lactate dehydrogenase (Rowsell, Snell, Carnie & Al-Tai, 1969).…”

Section: Enzyme Assaysmentioning

confidence: 99%

Metabolism of Threonine by Penicillia: Growth on Threonine as the Sole Carbon and Nitrogen Source

Willetts

1972

Journal of General Microbiology

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S U M M A R YTwo species of Penicillium were isolated from soil by their ability to grow aerobically on L-threonine as sole source of energy and cellular carbon and nitrogen. Threonine-grown fungi contained a highly active inducible L-threonine : NAD+ dehydrogenase and a significantly less active constitutive ' biosynthetic' threonine dehydratase, but possessed no L-t hreonine : acetaldehyde lyase activity. The 2-amino-3-oxobutyrate formed by initial dehydrogenation of threonine was subsequently cleaved in both fungi to acetyl-CoA and glycine in a coenzyme-Adependent cleavage catalysed by a 2-amino-3-oxobutyrate : CoA ligase which was inducibly synthesized during growth on threonine and not during growth on acetate plus glycine.During growth of both fungi on threonine, 14C from ~-[UJ~C]threonine was rapidly incorporated into glycine and malate, and thereafter into citrate, aspartate, glutamate, succinate and various other metabolites. The time-dependent distribution of 14C among metabolites in these short-term incubations with L-[U-~*C]-threonine showed that acetyl-CoA produced by the NADf plus coenzyme-Adependent cleavage of threonine was metabolized via the tricarboxylic acid cycle plus glyoxylate cycle.Comparative enzyme induction patterns after growth of both fungi on a wide range of carbon sources showed that glycine produced by the NAD+ plus coenzyme-A-dependent cleavage of threonine was metabolized via the glycerate pathway.There was no evidence from either comparative enzyme induction patterns or incorporation of 14C from ~-[U-l~C]threonine of aminoacetone production and further metabolism by both fungi, even though a small amount of this aminoketone appeared in culture media during growth on threonine. I N T R O D U C T I O NThe metabolism of L-threonine by fungi is previously unrecorded. Several alternative pathways of threonine catabolism have been recognized among different bacterial species. A pathway involving an initial L-threonine dehydratase (deaminating) and subsequent metabolism of the a-oxobutyrate produced via propionate to succinyl-CoA and hence the tricarboxylic acid cycle has been demonstrated in several bacteria (Whiteley, I 957). The alternative metabolism of threonine by L-threonine : acetaldehyde lyase to yield acetaldehyde and glycine has been recorded in a Bacillus species (Willetts & Turner, 1971) and also in a Pseudomonas species (Morris, I 969). A third pathway, the so-called ' aminoketone pathway', involving L-threonine : NAD+ dehydrogenase and subsequent metabolism of the initial dehydrogenation product, 2-amino-3-oxobutyrate, via aminoacetone to pyruvate, has been recorded in a Bacillus species (Willetts & Turner, 1970). A fourth pathway, also involving an initial L-threonine : NAD+ dehydrogenase, but the alternative subsequent

show abstract

Liver-L-alanine-glyoxylate and L-serine-pyruvate aminotransferase activities: an apparent association with gluconeogenesis

Cited by 94 publications

References 14 publications

Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine-NAD+ oxidoreductase

Bacterial catabolism of threonine. Threonine degradation initiated by L-threonine-NAD+ oxidoreductase

Targeted Disruption of the Mouse 3-Phosphoglycerate Dehydrogenase Gene Causes Severe Neurodevelopmental Defects and Results in Embryonic Lethality

Metabolism of Threonine by Penicillia: Growth on Threonine as the Sole Carbon and Nitrogen Source

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