ALKALINE INORGANIC PYROPHOSPHATASE OF MAIZE LEAVES

1. 1. Leaves of an albino mutant and of normal green seedlings of maize have high levels of readily extractable alkaline inorganic pyrophosphatase (EC 3.6.1.1) when grown under strong illumination. About one-tenth as much activity is found in both types of plants when grown in the absence of light. A brief illumination of dark-grown seedlings induces a large increase in readily extractable pyrophosphatase activity in the subsequent dark period. 2. 2. In light-grown maize the enzyme is localized in the chloroplasts but is readily washed out by aqueous solvents. The enzyme is highly specific for Mg2+ and PPi, and has optimal activity between pH 8 and 9. Leaf extracts of sorghum have similar high activity; many other plants, and other maize tissues have much less activity. © 1969.