Received February 3, 2005
Returned for revision March 7, 2005
Accepted March 13, 2005
Purification and Characterization of Adenosine Diphosphate Glucose Pyrophosphorylase from Maize/Potato Mosaics
Susan K. Boehlein , Aileen K. Sewell , Joanna Cross , Jon D. Stewart , and L. Curtis Hannah *
Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32611
Program in Plant Molecular and Cellular Biology and Horticultural Sciences, University of Florida, Gainesville, Florida 32611
Department of Chemistry, University of Florida, Gainesville, Florida 32611
* Corresponding author; email: hannah{at}ifas.ufl.edu.
Adenosine diphosphate glucose pyrophosphorylase (AGPase) catalyzes a rate-limiting step in starch biosynthesis. The reaction produces ADP-glucose and pyrophosphate from glucose-1-P and ATP. Investigations from a number of laboratories have shown that alterations in allosteric properties as well as heat stability of this enzyme have dramatic positive effects on starch synthesis in the potato (Solanum tuberosum) tuber and seeds of important cereals. Here, we report the characterization of purified recombinant mosaic AGPases derived from protein motifs normally expressed in the maize (Zea mays) endosperm and the potato tuber. These exhibit properties that should be advantageous when expressed in plants. We also present an in-depth characterization of the kinetic and allosteric properties of these purified recombinant AGPases. These data point to previously unrecognized roles for known allosteric effectors.
