Mn2+-sensitive and -insensitive forms of phosphoenolpyruvate carboxykinase (GTP).

R. I. Brinkworth, R. W. Hanson, F. A. Fullin, Vern L. Schramm

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) from rat liver cytosol is activated by micromolar concentrations of Mn2+ under conditions where GTP is present as the MgGTP complex and free Mg2+ is present in excess. The purified, homogeneous enzyme rapidly loses the ability to be activated by Mn2+ upon storage, incubation with oxidized glutathione, or incubation with Mn2+. These changes are prevented by reducing agents. Under certain conditions, phosphoenolpyruvate carboxykinase (Mr = 72,000) co-purifies with a protein of Mr = 29,000. This complex co-elutes on gel permeation chromatography but can be separated by chromatography on GTP-agarose in the presence of Mn2+. The Mr = 29,000 protein stabilizes the activity of the enzyme and protects against the changes which lead to the loss of the Mn2+ activation. These results suggest that the Mn2+ activation of P-enolpyruvate carboxykinase is dependent on the degree of oxidation of cysteine sulfhydryls. The role of the Mr = 29,000 protein in in vitro experiments is to stabilize the enzyme oxidation state which permits activation by Mn2+.

Original languageEnglish (US)
Pages (from-to)10795-10802
Number of pages8
JournalJournal of Biological Chemistry
Volume256
Issue number21
StatePublished - Nov 10 1981
Externally publishedYes

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Phosphoenolpyruvate Carboxykinase (GTP)
Chemical activation
Enzymes
Oxidation
Phosphoenolpyruvate
Proteins
Glutathione Disulfide
Reducing Agents
Gel permeation chromatography
Chromatography
Guanosine Triphosphate
Liver
Cytosol
Gel Chromatography
Cysteine
Rats
Experiments

ASJC Scopus subject areas

  • Biochemistry

Cite this

Mn2+-sensitive and -insensitive forms of phosphoenolpyruvate carboxykinase (GTP). / Brinkworth, R. I.; Hanson, R. W.; Fullin, F. A.; Schramm, Vern L.

In: Journal of Biological Chemistry, Vol. 256, No. 21, 10.11.1981, p. 10795-10802.

Research output: Contribution to journalArticle

Brinkworth, RI, Hanson, RW, Fullin, FA & Schramm, VL 1981, 'Mn2+-sensitive and -insensitive forms of phosphoenolpyruvate carboxykinase (GTP).', Journal of Biological Chemistry, vol. 256, no. 21, pp. 10795-10802.
Brinkworth, R. I. ; Hanson, R. W. ; Fullin, F. A. ; Schramm, Vern L. / Mn2+-sensitive and -insensitive forms of phosphoenolpyruvate carboxykinase (GTP). In: Journal of Biological Chemistry. 1981 ; Vol. 256, No. 21. pp. 10795-10802.
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