This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Levi, C. Articles by Preiss, J. Search for Related Content PubMed PubMed Citation Articles by Levi, C. Articles by Preiss, J. Agricola Articles by Levi, C. Articles by Preiss, J.

Articles

Regulatory Properties of the ADP-Glucose Pyrophosphorylase of the Blue-Green Bacterium Synechococcus 6301 ¹

^a Department of Biochemistry and Biophysics, University of California, Davis, California 95616

ADP-glucose was found to be the primary sugar nucleotide used for glycogen synthesis by Synechococcus 6301. ADP-glucose pyrophosphorylase was partially purified 12-fold from this blue-green bacterium. The enzyme was activated 8- to 25-fold by glycerate 3-phosphate. Fructose 6-phosphate, fructose 1,6-bisphosphate, 5'-adenylate, and adenosine diphosphate activated the enzyme, but less than glycerate 3-phosphate. The enzyme was inhibited by inorganic phosphate. The I_0.5 of phosphate was 0.072 mM, and in the presence of 2 mM glycerate 3-phosphate, increased to 1.8 mM. The substrate saturation curves for glucose 1-phosphate and ATP were hyperbolic in both the presence and absence of glycerate 3-phosphate or phosphate. The saturation curve for MgCl₂ was sigmoidal; 2 mM glycerate 3-phosphate decreased the sigmoidicity from a Hill slope n value of 5.6 to 2.8, and increased the MgCl₂ optimum from 3 mM to 6 to 7 mM.