E. coli asparate transcarbamoylase (ATCase) has a Hillcoefficient of 1.7 and Vmax 4.5 uM/min. The definition of Vmax isKcat * [Etot], where kcat is the rate constant for formation ofproduct. The measured value of kcat for this reaciton, which isdetermined in the absence of CTP, is 800 1/min. The dissociationconstant for the allosteric effector CTP from ATCase is 1 mM. WhenCTP is bound to ATCase the K(1/2) for asparate is 20 mM; when CTPis not bound to ATCase the K(1/2) for asparate is 5 mM.
a) Calculate what the concentration of total ATCase is under theconditions where Vmax was determined. Calculate how much ATCase ispresent with CTP bound and how much is present without CTP boundwhen the CTP concentration is 6 mM. Calculate how much ATCase ispresent with CTP bound and how much is present without CTP boundwhen the CTP concentration is 0.3 mM.
