Kimiko Sasaki

Polyriboadenylate synthesizing activity in chromatin of wheat seedlings

Abstract The occurrence of poly(A) polymerase was demonstrated in chromatin of wheat seedlings. The optimum pH was about 8.0. The activity was depressed by the treatment of chromatin with pronase or deoxyribonuclease, and it was sensitive to ribonuclease. AMP, ADF, inorganic pyrophosphate, CTP, GTP, UTP, dATP, dCTP, dGTP, dTTP, and lysine inhibited the activity, while aspartate stimulated it. Rifampicin significantly, and actinomycin D insignificantly inhibited the activity. Difference of the susceptibilities to dTTP and to tryptophane indicates that poly(A) polymerase is unlike RNA polymerase.

Low-temperature-dependent ribonuclease in chromatin of winter wheat seedlings

Summary A kind of ribonuclease having an optimun temperature of about 15°C was detected in chromatin of seedlings of a species of winter wheat, besides another kind having an optimum temperature of about 30°C. The optimum pH was about 8.0. The activity of ribonuclease was inhibited by bontonite and DNA, and was stimulated by cyclic AMP. The low-temperature-dependent activity was thermolabile.