Adenosine Diphosphoglucose-Starch Glucosyltransferases from Developing Kernels of Waxy Maize

TWO ADENOSINE DIPHOSPHOGLUCOSE: alpha-1,4-glucan alpha-4-glucosyl-transferases were extracted from kernels of waxy maize harvested 22 days after pollination and separated by gradient elution from a diethylaminoethyl-cellulose column. Both fractions could utilize amylopectin, amylose, glycogen, maltotriose and maltose as primers. The rate of glucose transfer from adenosine diphosphoglucose to rabbit liver glycogen of fraction II was 78% of the rate of glucose transfer to amylopectin, but with fraction I the rate of transfer of glucose to rabbit liver glycogen was 380% of that observed to amylopectin. Glucan synthesis in the absence of added primer was found in fraction I in the presence of 0.5 m sodium citrate and bovine serum albumin. The unprimed product was a methanol-precipitable glucan with principally alpha-1,4 linkages and some alpha-1,6 linkages, and its iodine spectrum was similar to that of amylopectin.