Interaction of rat liver alanine aminotransferase with L-proline

Segal, Harold L.; Abraham, George J.; Matsuzawa, Takeo

doi:10.1016/0006-291x(68)90713-4

Cited by 8 publications

(2 citation statements)

References 5 publications

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“…Ligand induced stabilization against heat inactivation may also be explained by invoking protection by the substrate of heat labile groups at or near the active site on the enzyme molecule. Similar explanations for substrate protection have been given by several workers (Grisolia and Joyce, 1960;Segel et al, 1968;Theorell and Tatemoto, 1971;Citri, 1973).…”

Section: Discussionsupporting

confidence: 78%

Allosteric serine hydroxymethyltransferase from monkey liver: Temperature induced conformational transitions

1981

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The homogeneous serine hydroxymethyltransferase from monkey liver was optimally activate at 60°C and the Arrhenius plot for the enzyme was nonlinear with a break at 15°C. The monkey liver enzyme showed high thermal stability of 62°C, as monitored by circular dichroism at 222 nm, absorbance at 280 nm and enzyme activity. The enzyme exhibited a sharp cooperative thermal transition in the range of 50°-70° (T m = 65°C), as monitored by circular dichroism. L-Serine protected the enzyme against both thermal inactivation and thermal disruption of the secondary structure. The homotropic interactions of tetrahydrofolate with the enzyme was abolished at high temperatures (at 70°C, the Hill coefficient value was 1.0). A plot of h values vs. assay temperature of tetrahydrofolate saturation experiments, showed the presence of an intermediate conformer with an h value of 1.7 in the temperature range of 45°-60°C. Inclusion of a heat denaturation step in the scheme employed for the purification of serine hydroxymethyltransferase resulted in the loss of cooperative interactions with tetrahydrofolate. The temperature effects on the serine hydroxylmethyltransferase, reported for the first time, lead to a better understanding of the heat induced alterations in conformation and activity for this oligomeric protein.

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Section: Discussionsupporting

confidence: 78%

Allosteric serine hydroxymethyltransferase from monkey liver: Temperature induced conformational transitions

1981

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“…The effectiveness of (2S,4S)-(aminooxy)proline at reducing AlaAT activity at 10 -7 M and lower drug concentrations supports this belief. Despite its bulky, rigid five-membered heterocyclic structure, which bears little structural resemblance to the substrates for this enzyme, its free aminooxy and carboxyl groups conferred significant capacity to inhibit aminotransferase activity, even more than had been attributed to the parent compound, L-proline, in rat liver (22). In addition, our intention was to utilize an analog of (2S,4S)-(aminooxy)proline having defined or fixed stereochemistry, i.e., transoid arrangement of the -ONH 2 and -COOH groups, in order to obtain information on the conformation required for inhibitor binding to the enzyme.…”

Section: Discussionmentioning

confidence: 99%

Structure−Activity Studies of l-Canaline-Mediated Inhibition of Porcine Alanine Aminotransferase

Worthen

Ratliff

Rosenthal

et al. 1996

Chem. Res. Toxicol.

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L-Canaline [L-2-amino-4-(aminooxy)butanoic acid] (L-CAN) and a family of eleven structurally related analogs were synthesized and evaluated for their inhibitory effect on PLP-dependent alanine aminotransferase (AlaAT) (EC 2.6.1.2) obtained from porcine heart. These congeners were selected to determine the stereochemical, aliphatic chain length, and aminooxy substitutional effects on L-CAN-mediated inhibition of AlaAT activity. L-CAN was the most effective inhibitor of the tested compounds; 10(-7) M L-CAN elicited a 55% reduction in AlaAT activity after a 5 min exposure. This deleterious effect results from the ability of L-CAN to react avidly with PLP moiety of the enzyme to form a stable, L-CAN-PLP oxime. In contrast, the methyl and ethyl esters of L-CAN reduced AlaAT activity by only 8% and 6%, respectively. While all of the L-enantiomeric forms of the tested compound were more potent AlaAT inhibitors than their corresponding D-stereoisomers, the D-enantiomers, particularly D-canaline, were active. Chain shortening or lengthening dramatically curtailed L-CAN-mediated loss in AlaAT activity, but the replacement of the alpha-amino group with a hydrogen was of little consequence in this regard. AlaAT was treated with L-CAN in the presence of free PLP to assess PLP capacity to protect AlaAT against 10(7) M L-CAN-dependent inactivation. L-CAN retained approximately two-thirds of its inhibitory ability in the presence of equimolar PLP, but AlaAT inhibition was reduced 90% by a 10-fold excess of PLP over L-CAN.

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Conformational Adaptability in Enzymes

Citri¹

1973

Advances in Enzymology - And Related Areas of Molecular Biology

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Interaction of rat liver alanine aminotransferase with L-proline

Cited by 8 publications

References 5 publications

Allosteric serine hydroxymethyltransferase from monkey liver: Temperature induced conformational transitions

Allosteric serine hydroxymethyltransferase from monkey liver: Temperature induced conformational transitions

Structure−Activity Studies of l-Canaline-Mediated Inhibition of Porcine Alanine Aminotransferase

Conformational Adaptability in Enzymes

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