Abstracts Biological Sciences

Effect of a carob inhibitor on alpha-amylase and acid phosphatase in barley endosperm

by Douglas H. C. Northcutt

The development of alpha amylase and phosphatase in barley endosperm was studied in the presence and absence of an inhibitory fraction from an extract of carob fruit (Ceratonia). The amounts of the two enzymes were measured in both the medium and the seeds. The inhibitor reduced the amount of alpha-amylase in the medium at all time intervals measured over a period of 57 hours. There was no concurrent reduction in the seeds. Instead, ex-amylase from seeds incubated either with GA3 alone or with GA3 plus inhibitor increased to a relatively high level by 26 to 30 hours. Total enzyme content was approximately the same whether the inhibitor was added or not. Acid phosphatase in the medium was also reduced by the inhibitor. There was little difference in phosphatase content between the seeds incubated in media containing GA3 alone and those in GA3 plus inhibitor. High concentrations of inhibitor completely blocked the appearance of the enzyme in the medium. If the seeds were then washed with water and placed in fresh media with GA3 but no inhibitor, they would produce phosphatase. The presence of the inhibitor did not permanently affect the enzyme synthesizing ability of the seeds. Addition of inhibitor at various times during incubation resulted in a subsequent reduction of the amount of acid phosphatase produced. These data indicate that fraction C from carob has different effects on each of the two enzymes studied. In the case of alpha-amylase secretion seems to be blocked, and in acid phosphatase synthesis seems to be inhibited. The inhibition of phosphatase appears to be at the protein synthesis level rather than the RNA level.