THE INHIBITION OF FUNCTIONAL RNA SYNTHESIS IN CHLORELLA PYRENOIDOSA BY 6‐METHYL PURINE

Abstract

SummaryAddition of 10‐3 M 6‐methyl purine caused immediate inhibition of total RNA synthesis in Chlorella pyrenoidosa, 211‐8p, whereas inhibition of total protein synthesis developed progressively with time. 50% inhibition of adenine incorporated into RNA, and of de novo isocitrate lyase synthesis, was caused by 5 × 10‐5 M 6‐methyl purine, but a ten‐fold higher concentration was required to give a similar inhibition of total RNA synthesis. The inhibition of isocitrate lyase synthesis was reversed competitively by adenine. Isocitrate lyase synthesis was inhibited by 91% at a concentration of 10‐3 M 6‐methyl purine, which gave only 12% inhibition of glucose respiration. It is suggested that 6‐methyl purine acts by replacing adenine in RNA metabolism. It is concluded that 6‐methyl purine may be used as an inhibitor of functional RNA synthesis in Chlorella and that the synthesis of isocitrate lyase during the cell cycle is dependent upon concurrent transcription.