The position of an essential tyrosine residue in the polypeptide chain of aspartate transaminase

Polyanovsky, O.L.; Demidkina, Tatyana V.; Egorov, C.A.

doi:10.1016/0014-5793(72)80356-9

Cited by 17 publications

(8 citation statements)

References 8 publications

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“…The amino acid residues lys-258 (the cofactor binding site [ 10] ), tyr-40 [11] and cys-390 [12] may be at or near the active site. The role of these residues in catalysis cannot, however, be inferred without detailed information on the three dimensional structure of the molecule.…”

Section: Resultsmentioning

confidence: 99%

“…It should be emphasized that knowledge of the primary structure does not advance our understanding of the mechanism of catalysis by the enzyme. The amino acid residues lys-258 (the cofactor binding site [ 10] ), tyr-40 [11] and cys-390 [12] may be at or near the active site. The role of these residues in catalysis cannot, however, be inferred without detailed information on the three dimensional structure of the molecule.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The primary structure of aspartate aminotransferase from pig heart muscle determined in part using a protease with specificity for lysine

Doonan¹,

Doonan²,

Hanford³

et al. 1974

FEBS Letters

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The primary structure of aspartate aminotransferase from pig heart muscle determined in part using a protease with specificity for lysine

Doonan¹,

Doonan²,

Hanford³

et al. 1974

FEBS Letters

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“…Our model agrees, because the A face of the pyridine ring and the si side of the C4'=-N bond are shielded from solvent. (ii) Identified residues in or near the active site include: Arg-292 as a substrate-anchoring site (49); (5,50) and an associated tyrosine (5), (51); Tyr-70 (we have Tyr7O*) and also Cys-390, which were specifically crosslinked to Lys-258 by a bifunctional reagent (52). (iii) Chemical or spectroscopic results have suggested that the following groups lie in the active center: a tyrosine by specific nitration in the apoenzyme (53), a tryptophan by fluorescence quenching upon pyridoxal-P binding (54), a histidine by photooxidation (55), a "positive pocket" around the coenzyme phosphate (56), and an arginine (49,57,58) as the anchor of the substrate w-carboxyl group (58).…”

Section: H H H H H H H H H H H H H H H H H H H H H H H H H H H mentioning

confidence: 99%

Three-dimensional structure of a pyridoxal-phosphate-dependent enzyme, mitochondrial aspartate aminotransferase.

Ford¹,

Eichele²,

Jansonius³

1980

Proc. Natl. Acad. Sci. U.S.A.

244

139

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X-ray diffraction studies to 2.8A resolution have yielded the three-dimensional structure of mitochondrial aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1), an isologous a2 dimer (M, = 2 X 45,000) The subunits are rich in secondary structure and contain two domains, one of which anchors the coenzyme, pyridoxal 5'-phosphate. Each active site lies between the subunits and is composed of residues from both of them.Aspartate aminotransferase (AATase; L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1) is the most studied of the vitamin B-6-dependent enzymes (1, 2). These enzymes catalyze a wide variety of transformations in amino acid metabolism. AATase effects the reversible transfer of an amino group from L-aspartate or L-glutamate to the a-keto acids a-ketoglutarate and oxalacetate. In the course of the double displacement reaction (3, 4) the coenzyme shuttles between the pyridoxal-P form (bound via an aldimine linkage to the E-amino group of a lysine) and the pyridoxamine-P form. "Syncatalytic" conformational changes occur in the enzyme matrix (5-7). Various coenzyme-substrate intermediates are identified by characteristic absorption and circular dichroism spectra (2, 8). The stereochemistry of pyridoxyl-catalyzed reactions has been probed (9), and a dynamic reaction mecha'nism has been proposed (10).Two homologous, genetically independent isozymes of AATase have been found in animal tissues, one in the cytosol (cAATase), the other in the mitochondrial matrix (mAATase). Both are a2 dimers of about 2 X 400 amino acids. The amino acid sequences of the pig (11-13) and chicken (refs. 14 and 15; U. Hausner, K. J. Wilson, and P. Christen, personal communication) isozymes are known or have been almost completely elucidated. Crystallized AATase offers an exceptional opportunity for the study of interactions amongst protein, coenzyme, and substrates during catalysis. The crystalline enzyme is catalytically competent (16). Single-crystal microspectrophotometric studies on cAATase (17, 18) and mAATase (16,19) have permitted the recognition of several reaction intermediates and the evaluation of some dissociation constants and kinetic parameters (19). Now a detailed picture of the enzyme is emerging from X-ray studies of such crystals. The high-resolution X-ray analyses of cAATase from chicken (20) and pig (21) are near completion. Here we report the three-dimensional structure of chicken mAATase in the internal aldimine form (pyridoxal-5'-P-enzyme) as revealed by a 2.8-A resolution X-ray study. RESULTS Structure determinationChicken mAATase crystallizes in a triclinic unit cell that contains one a2 dimer (22) whose subunits are related by a noncrystallographic dyad (23). Diffraction data to 2.8-A resolution of the native protein and the derivatives listed in Table 1 were collected on a CAD4F diffractometer (Enraf-Nonius, Delft, Netherlands). Previously found heavy atom sites (23) were reevaluated by difference Fourier maps. They were refined by alternate cycles of multiple i...

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“…It has been shown that Cys-45 is situated in a region of the enzyme molecule that is conformationally sensitive to interactions of the active site with specific ligands [10]. The residue is situated in the neighbourhood of the functionally important Tyr-40 which undergoes nitration on inactivation of the enzyme with tetranitromethane [ 11,12]. Despite its presumable vicinity to the active site, modification of Cys-45 does not impair the enzyme's catalytic properties.…”

Section: Discussionmentioning

confidence: 99%

Location of exposed and buried cysteine residues in the polypeptide chain of aspartate aminotransferase

Polyanovsky

Носиков

Deyev³

et al. 1973

FEBS Letters

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The position of an essential tyrosine residue in the polypeptide chain of aspartate transaminase

Cited by 17 publications

References 8 publications

The primary structure of aspartate aminotransferase from pig heart muscle determined in part using a protease with specificity for lysine

The primary structure of aspartate aminotransferase from pig heart muscle determined in part using a protease with specificity for lysine

Three-dimensional structure of a pyridoxal-phosphate-dependent enzyme, mitochondrial aspartate aminotransferase.

Location of exposed and buried cysteine residues in the polypeptide chain of aspartate aminotransferase

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