RecA protein provides the functional link between DNA damage and the SOS response by displacing the LexA protein from its operator sites on the SOS genes.  RecA does so by:

#Question id: 629

#Unit 1. Molecules and their Interaction Relevant to Biology

In the presence of a fixed concentration of a competitive inhibitor, which of the following would best characterize an enzyme-catalyzed reaction when the concentration of the substrate is increased?

#Question id: 630

#Unit 1. Molecules and their Interaction Relevant to Biology

In case of competitive inhibition, plots of Km against [Io] fixed [Eo] have

#Question id: 631

#Unit 1. Molecules and their Interaction Relevant to Biology

Two curves showing the rate versus substrate concentration are shown below for an enzyme-catalyzed reaction. One curve is for the reaction in the presence of substance X. The other curve is for data in the absence of substance X. Examine the curves and tell which statement below is false.

#Question id: 633

#Unit 1. Molecules and their Interaction Relevant to Biology

An amino acid transporter protein is responsible for the transport of a specific amino acid across a membrane. The KI values of several competitive inhibitors of the amino acid transporter are shown above. Based on these data, which of the following is most likely the amino acid transported by this protein?

#Question id: 634

#Unit 1. Molecules and their Interaction Relevant to Biology

An enzyme has a Vmax of 50 micromol product formed (minute x mg protein)-1 and a Km of 10 microM for the substrate. When a reaction mixture contains the enzyme and 5 microM substrate, which of the following percentages of the maximum velocity will be closest to the initial reaction rate?

#Question id: 635

#Unit 1. Molecules and their Interaction Relevant to Biology

The enymatic rate constant (kcat/Km) of orotidine 5ʹ-phosphate decarboxylase is 6 x 10⁷ M^-1s^-1 and the nonenzymatic rate constant (kn) is 3 x 10^-16 s^-1.  What is the value of the enzymeʹs catalytic proficiency?