Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications

Yeast glycogen synthetase (uridine diphosphate glucose : glycogen α-4-glucosyltransferase) is inhibited at neutral pH by rather high concentrations of several anions, and addition of glucose 6-phosphate reverses this effect. It has now been found that many substances are much more effective inhibito...

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Autores principales: Rothman, Lucía B., Cabib, Enrique
Publicado: 1967
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00062960_v6_n7_p2107_Rothman
http://hdl.handle.net/20.500.12110/paper_00062960_v6_n7_p2107_Rothman
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00062960_v6_n7_p2107_Rothman
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spelling paper:paper_00062960_v6_n7_p2107_Rothman2023-06-08T14:30:51Z Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications Rothman, Lucía B. Cabib, Enrique Yeast glycogen synthetase (uridine diphosphate glucose : glycogen α-4-glucosyltransferase) is inhibited at neutral pH by rather high concentrations of several anions, and addition of glucose 6-phosphate reverses this effect. It has now been found that many substances are much more effective inhibitors at pH 6, the reported value for the yeast cell, than at pH 7.5. At the acidic pH, 5 mM adenosine triphosphate, adenosine diphosphate, or guanosine triphosphate inhibits the enzyme about 90%. Glucose 6-phosphate acts as reactivator in this case too. By several criteria these nucleotides are shown to act as allosteric inhibitors. A possible mechanism of regulation of glycogen synthesis is proposed, according to which the combined concentrations of adenosine triphosphate plus adenosine diphosphate would always be sufficient for almost complete inhibition of the enzyme in the absence of glucose 6-phosphate. The concentration of phosphoric ester would then determine the activity of the enzyme. At high adenosine triphosphate: adenosine monophosphate ratios, phosphofructokinase would be inhibited and glucose 6-phosphate would accumulate, thus relieving the inhibition of glycogen synthesis. The opposite effect would take place at low adenosine triphosphate:adenosine monophosphate ratios. Ammonium ion, when present, would also act on the phosphofructokinase reaction, helping to channel the carbon of glucose toward the formation of amino acids and other nitrogenous substances. Fil:Rothman, L.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Cabib, E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1967 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00062960_v6_n7_p2107_Rothman http://hdl.handle.net/20.500.12110/paper_00062960_v6_n7_p2107_Rothman
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description Yeast glycogen synthetase (uridine diphosphate glucose : glycogen α-4-glucosyltransferase) is inhibited at neutral pH by rather high concentrations of several anions, and addition of glucose 6-phosphate reverses this effect. It has now been found that many substances are much more effective inhibitors at pH 6, the reported value for the yeast cell, than at pH 7.5. At the acidic pH, 5 mM adenosine triphosphate, adenosine diphosphate, or guanosine triphosphate inhibits the enzyme about 90%. Glucose 6-phosphate acts as reactivator in this case too. By several criteria these nucleotides are shown to act as allosteric inhibitors. A possible mechanism of regulation of glycogen synthesis is proposed, according to which the combined concentrations of adenosine triphosphate plus adenosine diphosphate would always be sufficient for almost complete inhibition of the enzyme in the absence of glucose 6-phosphate. The concentration of phosphoric ester would then determine the activity of the enzyme. At high adenosine triphosphate: adenosine monophosphate ratios, phosphofructokinase would be inhibited and glucose 6-phosphate would accumulate, thus relieving the inhibition of glycogen synthesis. The opposite effect would take place at low adenosine triphosphate:adenosine monophosphate ratios. Ammonium ion, when present, would also act on the phosphofructokinase reaction, helping to channel the carbon of glucose toward the formation of amino acids and other nitrogenous substances.
author Rothman, Lucía B.
Cabib, Enrique
spellingShingle Rothman, Lucía B.
Cabib, Enrique
Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications
author_facet Rothman, Lucía B.
Cabib, Enrique
author_sort Rothman, Lucía B.
title Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications
title_short Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications
title_full Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications
title_fullStr Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications
title_full_unstemmed Allosteric properties of yeast glycogen synthetase. II. The effect of pH on inhibition and its physiological implications
title_sort allosteric properties of yeast glycogen synthetase. ii. the effect of ph on inhibition and its physiological implications
publishDate 1967
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00062960_v6_n7_p2107_Rothman
http://hdl.handle.net/20.500.12110/paper_00062960_v6_n7_p2107_Rothman
work_keys_str_mv AT rothmanluciab allostericpropertiesofyeastglycogensynthetaseiitheeffectofphoninhibitionanditsphysiologicalimplications
AT cabibenrique allostericpropertiesofyeastglycogensynthetaseiitheeffectofphoninhibitionanditsphysiologicalimplications
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