The synthesis in vitro of valine and isoleucine from pyruvate and α-ketobutyrate in neurospora

Wagner, Robert P.; Bergquist, Arloa; Barbee, T.

doi:10.1016/0304-4165(65)90014-0

Cited by 19 publications

(1 citation statement)

References 12 publications

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“…The precursors of branched-chain amino acids are fomed by condensation of pyruvate and a-ketobutyrate with a two-carbon derivative of diphosphothiamine (active acetaldehyde). It has been suggested that a differential affinity of the enzyme for the two kinds of substrates may also have a regulatory role (16).…”

Section: Resultsmentioning

confidence: 99%

Induced Phenotypic Resistance to Valine in Mycobacterium pellegrino

Horváth¹,

Szentirmai²,

Zsadányi³

1967

J Bacteriol

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Valine coordinately increases the levels of three of the enzymes participating in the biosynthesis of isoleucine and valine in Mycobacterium pellegrino. The amount of valine required for end-product induction depends on the condition of the cells. Isoleucine inhibits the effect of valine. Acetohydroxy acid synthetase, the enzyme catalyzing the first common step in the biosynthesis of valine and isoleucine, is inhibited by valine. The induction effect of valine appears to be due to its ability to inhibit the activity of this enzyme, thus causing isoleucine deficiency, which in turn leads to derepression. This conclusion is supported by the fact that valine, under certain conditions, inhibits growth.

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Section: Resultsmentioning

confidence: 99%

Induced Phenotypic Resistance to Valine in Mycobacterium pellegrino

Horváth¹,

Szentirmai²,

Zsadányi³

1967

J Bacteriol

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Multienzym‐Komplexe

Henning

1966

Angewandte Chemie

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Multienzyme Complexes

Henning

1966

Angew. Chem. Int. Ed. Engl.

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In 1948 D. E. Green[21 termed the mitochondria1 enzymes the cyciophorase complex, in order, as he later commented[31 " . . . to signify that the complex was a unit of enzyme action and not a chance mixture of several hundred enzymes. . . . this complex was visualized as aa organized mosaic of enzymes in which each of the large number of component enzymes was uniquely located to permit efficient implementation of consecutive reaction sequences". These words contain the concept of the multienzyme complex: ordered association (not involving peptide linkages) of various enzymes that catalyse successive steps in a reaction sequence. The present paper deals with recent findings regarding the properties of such complexes, and the question whether the concept represents a biological principle is discussed.Predominantly protein-chemical aspects of the association of enzymes were recently described by Sund and Weber [41, and the "macromolecular organization of enzywe systems" by Reed a n d Cox[sl.I. Multienzyme Complexes in a Narrower Sense Tryptophan SynthetaseA clear and relatively simple example is the tryptophan synthetase from Escherichia coli. In the presence of pyridoxal phosphate, the enzyme catalyses the last step [Eq. (a)] in the reaction chain leading to the biosynthesis of tryptophan : There is strong evidence that the catalytically active centers of the respective complementary proteins are not involved in the activation of A in reaction (b) and in that of B in reaction (c). Protein B which has lost its enzymatic activity as a result of mutation canactivate A in reaction (b) in the same way as unaltered protein B, while the reverse is true of A which has been inactivated by mutation. Moreover, the activity of B in reaction (c) is increased by a factor of about 20 in the presence of a high concentration of NH4+ ions 1141. Finally, Hatunuka [8] U.

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The synthesis in vitro of valine and isoleucine from pyruvate and α-ketobutyrate in neurospora

Cited by 19 publications

References 12 publications

Induced Phenotypic Resistance to Valine in Mycobacterium pellegrino

Induced Phenotypic Resistance to Valine in Mycobacterium pellegrino

Multienzym‐Komplexe

Multienzyme Complexes

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