Further Experiments on the β-Amylase-Containing Lysosomes of Wheat Aleurone Cells

Abstract

The presence of hydrolytic enzymes in sedimentable fractions (lysosomes) of homogenized gibberellic acid (GAS)-treated wheat aleurone tissue has been further examined. Non-specific binding of free α-amylase (EC 3.2.1.1) to any organelle did not occur when added before homogenization to aleurone tissue either treated with GA₃ or untreated, nor when amylose was added to GA₃-treated tissue. The distribution of sedimentable α-amylase between different centrifugal fractions could be controlled, however, by varying the concentrations of calcium or chelating agents in the grinding medium. The concentration of GA*3 applied to aleurone tissue altered neither the percentage nor the distribution of α-amylase recovered in the various particulate fractions. Of the α-amylase appearing in the supernatant fraction, a large proportion appears to be located in the cell wall and is inactivated by acid treatment prior to homogenization, confirming previous reports. Tissue treated in this way yields more than 80% of the recoverable enzyme in sedimentable fractions.