Question

2. (6 points) A wild-type protein was tested for its ability to fold under several concentrations of denaturant. Two mutants of this protein were made by making a one residue substitution and then also tested under similar conditions as the wild-type. Given the two curves below, interpret how the changed residue in mutant 1 and mutant 2 affect the protein folding nucleus. Assume Kapp is measured in s-1 in Kapp in Kap [denaturant [denaturant]

Answer 1

The given image is the 'chevron plot', showing the rate of protein denaturation when treated with a denaturant. Concentration of denaturant is given in' X axis' and the measure of denaturation is in 'Y axis'. There are three faces in the graph. That folding zone, transition zone and unfolding zone. All these 3 zones can be seen in the image given below.

a folding zone b-> Midtransition zone cUnfolding zone In Kapp Scanned with CamScanner c Denatugant)

In mutant 2 the substitution of one residue caused the  unfolding to be start at the same denaturant concentration as in the wild type. But it enter into the transition zone and completes the process of unfolding at a relatively lower concentration of the denaturant, when compared with the wild type. The mutant 1 here needs a little more denaturant concentration to start the unfolding and to enter in the transition zone than the wild type. But during the course, it completes the process of denaturation at the same range of denaturant concentration needed by the wild type. Here, due to the. substitution process , mutant 2 needs a lesser concentration of denaturant to complete the process of unwinding. But in mutant 2, it required relatively more concentration of denaturant to initiate the process of unwinding but completes at same denaturant concentration as in wild type.