The development of ribonuclease and acid phosphatase during germination of Pisum arvense.

1. Development of ribonuclease activity in the cotyledons of germinating peas is biphasic, the time of appearance of the two phases depending on the conditions of growth. 2. Acid phosphatase exhibits a single phase of development. 3. Cycloheximide inhibits development of ribonuclease activity in phase II but not in phase I. 4. (14)C-labelled amino acids are not incorporated into ribonuclease isolated during phase I. 5. The buoyant density of ribonuclease isolated during phase I is not affected by imbibition of the seed in 80% deuterium oxide. 6. Acid phosphatase was isolated from the supernatant fraction of the cotyledons of germinating peas and partially purified. 7. Development of acid phosphatase activity during germination is inhibited by treatment of the seed with cycloheximide or actinomycin D. 8. Partial purification of acid phosphatase from peas germinated in the presence of (14)C-labelled amino acids suggests that the enzyme is radioactively labelled. 9. Germination of peas in the presence of 80% deuterium oxide results in an increase in the buoyant density of acid phosphatase. 10. The results suggest that increase in ribonuclease activity during the first 4 days of germination does not result from synthesis of protein de novo, but that the corresponding increase in acid phosphatase activity does result from synthesis de novo.