Changes in phosphoglucose isomerase activity in a developmental system

Abstract

Phosphoglucose isomerase activity was identified and partially characterized in the root apex of Zea mays, utilizing homogenates and frozen, dried, 50 μ serial sections from the first two millimeters of primary roots. These sections were analyzed for dry weight, protein content and PGI activity. The determinations were related to the number of cells in each section. On the basis of dry weight, protein content or per cell, higher PGI activity was demonstrated in the rootcap than was demonstrated in the root proper. Some evidence was obtained to suggest that a more active isomerase in the rootcap could be responsible for this high level of activity. An 18- to 19-fold purification of the enzyme was achieved by starch gel electrophoresis. Changes in PGI activity along the developmental axis of the root indicated a low level of activity in the region of cell division and a general increase in activity in the region of cell enlargement.