Kinetic studies of beta-galactosidase induction

Abstract

The kinetics of beta-galactosidase induction in E. coli ML 3 have been studied. Following addition of inducer, the rate of enzyme synthesis accelerates from the uninduced to a steady-state rate. At saturating concentration of inducer the time constant (T(c)) for this process is 2.5 to 3 minutes. With decreasing inducer concentration (I), increasing time constants are observed. I/I + K' approximates I/T(c). The steady-state rate of beta-galactosidase synthesis is approximated by I(2)/I(2) + K(2). K' and K have been estimated for IPTG and TMG. The kinetics of beta-galactosidase production after the removal of inducer by dilution or after the addition of glucose have been investigated. A transition time of 2.5 to 3 minutes is observed before enzyme synthesis slows or stops. These results are consistent with the hypothesis that the enzyme-forming unit is unstable.