Enzymic decomposition of the active intermediate in citrulline synthesis

Grisolı́a, Santiago; Marshall, Richard O.

doi:10.1016/0006-3002(54)90212-7

Cited by 14 publications

(4 citation statements)

References 2 publications

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“…Unlike alkaline phosphatases and low M r acidic phosphatases, the enzyme is unable to hydrolyse any phosphate ester or organic anhydride and is structurally different from alkaline phosphatase [5] and low M r acidic phosphatases [6]. Acylphosphatase activity was first described in 1946 by Lipmann [7] and subsequently investigated, in the urea cycle studies, as the activity responsible for carbamoylphosphate hydrolysis [8,9]. After the discovery of the carbamoylphosphatase activity in rat liver, similar activities were described in many tissues and in E. coli [10]; in addition, it was soon evident that the carbamoylphosphatase activity was due to the same enzyme responsible for the acetylphosphate hydrolysis previously described by Lipmann.…”

Section: Overviewmentioning

confidence: 99%

Insights into acylphosphatase structure and catalytic mechanism

Stefani¹,

Taddei²,

Ramponi³

1997

CMLS, Cell. mol. life. sci.

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Acylphosphatase is one of the smallest enzymes known (about 98 amino acid residues). It is present in organs and tissues of vertebrate species as two isoenzymes sharing over 55% of sequence homology; these appear highly conserved in differing species. The two isoenzymes can be involved in a number of physiological processes, though their effective biological function is not still certain. The solution and crystal structures of different isoenzymes are known, revealing a close packed protein with a fold similar to that shown by other phosphate-binding proteins. The structural data, together with an extended site-directed mutagenesis investigation, led to the identification of the residues involved in enzyme catalysis. However, it appears unlikely that these residues are able to perform the full catalytic cycle: a substrate-assisted catalytic mechanism has therefore been proposed, in which the phosphate moiety of the substrate could act as a nucleophile activating the catalytic water molecule.

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Section: Overviewmentioning

confidence: 99%

Insights into acylphosphatase structure and catalytic mechanism

Stefani¹,

Taddei²,

Ramponi³

1997

CMLS, Cell. mol. life. sci.

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“…Under certain pathologic conditions at least, mitochondrial carbamoyl phosphate could be released to the cytosol and used in several enzymic reactions, including pyrimidine biosynthesis [5,40 -441, glucose 6-phosphate synthesis catalyzed by glucose-6-phosphatase 1451 and hydrolytic degradation catalyzed by carbamoyl-phosphatase [46]. However, studies on hepatic pyrimidine biosynthesis by us [5] (unpublished observations) and also by Pausch et al [44] strongly suggest that the release of mitochondrial carbamoyl phosphate to the cytosol is negligible under physiological conditions.…”

Section: Regulatory Role Of Acetylglutamate In Urea Synthesismentioning

confidence: 99%

Role of Acetylglutamate in Ureotelism

Shigesada

Aoyagi

Tatibana

1978

European Journal of Biochemistry

100

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The level of N-acetyl-L-glutamate showed a diurnal rhythm, which was associated primarily with dietary ingestion. Since the hepatic level of arginine, activator for acetylglutamate, is one of the plausible principal factors responsible for the regulation of acetylglutamate level, the effect of arginine was further studied. The intraperitoneal administration of a large amount of arginine increased the level of acetylglutamate and the effect was augmented by the combined administration of glutamine. The arginine administration stimulated the hepatic synthesis of acetylglutamate as measured with [14C]glutamate as tracer, but did not affect the half-life (about 20 min) of the synthesized 14C-labeled acetylglutamate.The effect of arginine in raising the acetylglutamate level was also demonstrated in vitvo in isolated rat liver cells. On the other hand, pent-4-enoic acid, known to inhibit fatty acid oxidation and to decrease acetyl-CoA production in the liver, lowered the level of acetylglutamate in the rat liver cells. It was shown that the cellular ureogenic capacity, as measured with NH4Cl as nitrogen source, showed a close correlation with the varying levels of acetylglutamate, brought about by arginine or pent-4-enoic acid.The carbamoyl phosphate level, which may reflect the balance between its synthesis and utilization for citrulline synthesis, was low (about 1 nmol/g) and remained relatively constant in the livers of intact mice even when the rate of urea synthesis was expected to vary with changes in the dietary protein content. A transient increase in the level was brought about by agents expected to increase the synthesis or to inhibit the utilization, such as ammonia, N-acetylglutamate diethyl ester, or norvaline. These results, together with others, suggest that in intact animals the production of carbamoyl phosphate is coupled to its utilization for citrulline synthesis.

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“…Recently Marshall, Hall, and Cohen (1955) showed that compound X, an intermediate in citrulline synthesis by rat liver preparations (Grisolia and Cohen 1952), was identical with CAP. The enzyme reported by Grisolia and Marshall (1954) which split compound X was presumably a CAP-ase.…”

Section: Results (A) the Separation Of Carbamyl-adp Phosphoferasementioning

confidence: 99%

The Metabolism of Arginine in Serratia Marcescens II. Carbamy1-Adednosine Diphosphate Phosphoferase

Glasziou¹

1956

Aust. Jnl. Of Bio. Sci.

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Carbamyl-adenesine diphesphate (ADP) phosphoforase, an enzyme which eatalysos the synthosis and broakdown of oarbamyl phosphate (CAP), has beon purified 43-fold and obtained free of carbamyl phosphate phosphatase activity. ADP, but not. adenosine mOllophosphate, has been shown to be a sllbsLrate for the enzyme. Magnesium or manganous ions are requirod for activity. Inhibition by heavy metal cations and p-chloromorcuribenzoato indicate that, a sulpbydryl group is involved in catalysis.

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Enzymic decomposition of the active intermediate in citrulline synthesis

Cited by 14 publications

References 2 publications

Insights into acylphosphatase structure and catalytic mechanism

Insights into acylphosphatase structure and catalytic mechanism

Role of Acetylglutamate in Ureotelism

The Metabolism of Arginine in Serratia Marcescens II. Carbamy1-Adednosine Diphosphate Phosphoferase

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