Solubility of beta-Glucosidase in Homogenates of Sweetclover Leaves and Bean Hypocotyls.
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Biomedical subjects
Publications and source records attributed to T A Jaynes.
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A bound invertase and two soluble invertases are found in the developing endosperm of maize (Zea mays L.). The two soluble invertases can be separated on diethylaminoethyl-cellulose and Sephadex columns and distinguished by their kinetic constants. One soluble invertase, invertase I, is present from the 10- to 28-day stages of endosperm development with maximal activity per normal endosperm at the 12-day stage. In two endosperm mutant lines, shrunken-1 and shrunken-2, there is a second increase in invertase I activity later in development which could be a secondary effect caused by the abnormal metabolism in these lines. Another soluble invertase, invertase II, is present in the embryo upon germination and is also found in the very young developing endosperm (6-day stage). The third form of invertase, bound invertase, is present in the endosperm by the 6-day stage, and its activity remains approximately constant during development.
A protein present in the developing endosperm of maize (Zea mays L.) causes a loss of invertase activity under certain conditions of incubation. This protein, designated an inactivator, inactivates invertase I of maize even in the presence of other proteins. No inactivation of invertase II of maize or yeast invertase has been observed. The inactivator and invertase I are found only in the endosperm. The quantity of inactivator increases in the normal endosperm during development while invertase I activity decreases. However, the altered levels of invertase I activity in several endosperm mutant lines do not result from different quantities of inactivator. The inactivator can decrease invertase I activity during a preincubation period before addition of sucrose; inactivation is noncompetitive. Invertase I activity decreases curvilinearly with an increase in inactivator concentration. At high buffer concentrations or low inactivator concentrations in the reaction mixture, a latent period is observed when invertase I is not inactivated. Inactivation increases with an increase in temperature and a decrease in pH.