RT Journal Article SR Electronic(1) A1 PAYNE, J. W.YR 1972 T1 Variations in the Peptidase Activities of Escherichia coli in Response to Environmental Changes JF Microbiology, VO 71 IS 2 SP 281 OP 291 DO https://doi.org/10.1099/00221287-71-2-281 PB Microbiology Society, SN 1465-2080, AB Summary: The activities of soluble, intracellular Co2+ and Mn 2+ activated dipeptidases of Escherichia coli varied with the growth conditions. With chemostat cultures, potassium-limitation and oxygen depletion produced high peptidase activities whereas activities were low in carbon-limited cultures; the activity of carbon-limited organisms approximated to that of exponential-phase batch-grown organisms. The effect of growth conditions on the specific activity of soluble tripeptidase, which did not require cations for activity, was different from that found for the dipeptidases; the highest activity was again found in potassium-limited organisms but lowest activity occurred with nitrogen and magnesium limitation. The activities of all these peptidases were independent of the pH of growth, within the range pH 7·0 to 5·5. These results are discussed in relation to the utilization of peptides by growing organisms and to measurements of the turnover of protein during growth. , UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-71-2-281