Über die Darstellung und Konstitution der Salze der von Ornithin und Lysin abgeleiteten α‐Ketosäuren

Macholán, Lumír; Vencálková, Jiřina

doi:10.1002/cber.19630960127

Cited by 17 publications

(5 citation statements)

References 19 publications

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“…L-Glutamate 5-semialdehyde was derived from N2acetyl-L-glutamate 5-semialdehyde, prepared according to a described method (34) by acid hydrolysis in 3.5 M HCl and 100 C for 60 min. 2-Oxo-5-amino-valeric acid was synthesized as described (20). L-[U-I"C ]ornithine and [1-'4C ]2-oxoglutarate were received from the Radiochemical Centre, Amersham, England.…”

Section: Methodsmentioning

confidence: 99%

Dual role for N-2-acetylornithine 5-aminotransferase from Pseudomonas aeruginosa in arginine biosynthesis and arginine catabolism

Voellmy¹,

Leisinger²

1975

J Bacteriol

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In Pseudomonas aeruginosa N2-acetylornithine 5-aminotransferase (ACOAT), the fourth enzyme of arginine biosynthesis is induced about 15-fold by cultivating the organism on a medium with L-arginine as the sole carbon and nitrogen source. Synthesis of the enzyme is subject to catabolite repression by a variey of carbon sources. ACOAT from strain PAO 1 was purified over 40-fold to electrophoretic homogeneity. A molecular weight of approximately 110,000 was obtained by thin-layer gel filtration. Electrophoresis in sodium dodecyl sulfate gels gave a single band corresponding to a molecular weight of 55,000. Purified ACOAT catalyzes the transamination of N2-acetyl-L-ornithine as well as of L-ornithine with 2-oxoglutarate (Km values of 1.1, 10.0, and 0.7 mM, respectively). With N2-acetyl-ornithine as amino donor, the pH-optimum of the enzymatic reaction is 8.5; with L-ornithine as amino donor, 9.5. The catalytic properties of ACOAT as well as the regulation of its synthesis indicate that in P. aeruginosa this enzyme functions in the biosynthesis as well as in the catabolism of L-arginine.

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Section: Methodsmentioning

confidence: 99%

Dual role for N-2-acetylornithine 5-aminotransferase from Pseudomonas aeruginosa in arginine biosynthesis and arginine catabolism

Voellmy¹,

Leisinger²

1975

J Bacteriol

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“…a-Keto-5-aminovaleric acid was synthesized as the hydrochloride salt by the method of Hasse & Wieland (1960). This compound when dissolved in water at pH >4 spontaneously cyclizes to PCA (Cabello et al, 1964; Macholan & Vencalkova, 1963). NADPH from Boehringer-Mannheim and NADP+ from Sigma were used without further purification.…”

Section: Methodsmentioning

confidence: 99%

“…The observed rates for the enzymatic reduction of PCA were corrected for the nonenzymatic reaction occurring concurrently by measuring the rate of disappearance of NADPH under identical conditions in the absence of the enzyme. The blank reaction, which includes contributions from both the nonenzymatic reduction of PCA (Srinivasan et al, 1982;Meister et al, 1957) and general-acid-catalyzed decomposition of NADPH (Norris & Stewart, 1977), is usually less than 10% of the observed rates. In the reverse direction (eq 1), however, no reaction was observed in the absence of the enzyme.…”

Section: Methodsmentioning

confidence: 99%

Reversible reduction of an .alpha.-imino acid to an .alpha.-amino acid catalyzed by glutamate dehydrogenase: effect of ionizable functional groups

Srinivasan¹,

Fisher²

1985

Biochemistry

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The glutamate dehydrogenase catalyzed reduction of delta 1-pyrroline-2-carboxylic acid (PCA; an alpha-imino acid) with reduced nicotinamide adenine dinucleotide phosphate (NADPH) to give L-proline and NADP+ is employed as a model for the redox step of the corresponding enzyme-catalyzed reductive amination of alpha-ketoglutarate. We demonstrate the reversibility of the model reaction and measure its equilibrium constant. The pH profiles for the model reactions show that the active substrates are the N-protonated imino acid in one direction and the proline anion with a neutral amino group in the other. The V/K value for the imino acid reduction is enhanced by a group Z of pK = 8.6 in the enzyme-NADPH complex, while that for the proline reaction is unaffected by any such group in the enzyme-NADP+ complex. The following conclusions emerge from a comparison of the pH dependence of the rates for the model reactions with that for the oxidative deamination of L-glutamate [Rife, J. E., & Cleland, W. W. (1980) Biochemistry 19, 2328]. The N-protonated form of alpha-iminoglutarate and the conjugate base of glutamate are the active substrates. The redox step is not sensitive to the protonation state of the groups that catalyze the hydrolysis of bound alpha-iminoglutarate. The group Z, which facilitates the PCA reaction, plays no role in the binding of alpha-ketoglutarate. We propose a chemical mechanism for the glutamate reaction where an unprotonated enzyme group of pK = 5.2 in enzyme-NADPH catalyzes the conversion of the alpha-iminoglutarate to the carbinolamine.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…a-Keto-S-aminovaleric acid was synthesized as the hydrochloride salt (Hasse & Wieland, 1960). This compound spontaneously cyclizes to PCA upon dissolution in water at pH >2 (Cabello et al, 1964;Macholan & Vencalkova, 1963). NADPH from Boehringer-Mannheim and NADP+ from Sigma were used without further purification.…”

Section: Methodsmentioning

confidence: 99%

“…(NADPH) (Meister et al, 1957;Srinivasan et al, 1982). The nonenzymatic reaction, which proceeds at a measurable speed only in the forward direction, is shown in eq 1.…”

mentioning

confidence: 99%

Comparison of the energetics of the uncatalyzed and glutamate dehydrogenase catalyzed .alpha.-imino acid-.alpha.-amino acid interconversion

Srinivasan¹,

Fisher²

1985

Biochemistry

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The thermodynamic and activation parameters for the reduction of delta 1-pyrroline-2-carboxylic acid (an alpha-imino acid) by reduced nicotinamide adenine dinucleotide phosphate (NADPH) are compared with those for the reduction of the same imino acid by the glutamate dehydrogenase-NADPH complex. The enthalpies of activation and standard free energy changes for these two reactions are found to be virtually the same. The catalysis by the enzyme, expressed as the ratio of the reactivity of the enzyme--NADPH complex to that of NADPH itself in reducing the iminium ion, is entirely accounted for by a more favorable entropy of activation with enzyme--NADPH as the reductant. This entropic driving force is large enough to overcome the exergonic formation of the binary complex and still lead to considerable catalysis by glutamate dehydrogenase. Comparison of delta S not equal to and delta So values for the reduction of the iminium ion by NADPH suggests that the solvation of the transition state resembles that of the reactants, even though the substituent effects on rate have shown that the hydride transfer from the reduced coenzyme is complete at the transition state [Srinivasan, R., Medary, R. T., Fisher, H. F., Norris, D. J., & Stewart, R. (1982) J. Am. Chem. Soc. 104, 807]. The delta Go and delta S not equal to/delta So values for the reduction by the enzyme--NADPH complex indicate that this reaction has a fairly symmetric transition state, the solvation properties of which are intermediate between those of the reactants and those of the products.(ABSTRACT TRUNCATED AT 250 WORDS)

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Über die Darstellung und Konstitution der Salze der von Ornithin und Lysin abgeleiteten α‐Ketosäuren

Cited by 17 publications

References 19 publications

Dual role for N-2-acetylornithine 5-aminotransferase from Pseudomonas aeruginosa in arginine biosynthesis and arginine catabolism

Dual role for N-2-acetylornithine 5-aminotransferase from Pseudomonas aeruginosa in arginine biosynthesis and arginine catabolism

Reversible reduction of an .alpha.-imino acid to an .alpha.-amino acid catalyzed by glutamate dehydrogenase: effect of ionizable functional groups

Comparison of the energetics of the uncatalyzed and glutamate dehydrogenase catalyzed .alpha.-imino acid-.alpha.-amino acid interconversion

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