The Pool of Ribonucleoside Triphosphates in Synchronized Tetrahymena pyriformis

Abstract

SUMMARY: Two strains of Pseudomonas putida, S3 and P3, were shown to contain dehalogenase activity against monochloroacetate, dichloroacetate, 2-monochloropropionate and 2,2#-dichloro-propionate but differed markedly in their levels of enzyme activity. Strain S3 had activities of less than 1 μmol substrate converted (mg protein)⁻¹ h⁻¹ and was unable to grow on any of nine chlorinated compounds tested. Strain P3 had enzyme activities 10 to 40 times greater than those of strain S3 but was capable of growth only on 2-monochloropropionate and 2,2#-dichloropropionate. In strain P3, dehalogenase activity was induced by a number of chlorinated compounds other than those that acted as growth substrates. Strain P3 dehalogenase activity dehalogenated C-2 substituted compounds. The evidence of the dehalogenase activity profiles in chemostat cultures and from thermal denaturation experiments suggested that there was more than one dehalogenase enzyme in P. putida strain P3. In crude extract, the enzyme activity was optimal at pH 7.9 to 8.1 and apparent K_m values were in the millimolar range for the four major substrates, monochloroacetate, dichloroacetate, 2-monochloropropionate and 2,2#-dichloropropionate.