help biochem Several mutants of this enzyme were made to inc

help biochem

Several mutants of this enzyme were made to increase its catalytic efficiency. The following table gives the kinetics parameters obtained for these mutants.

1. Which mutant has a higher catalytic efficiency than the wild-type enzyme?

A. Mut 1

B. Mut 2

C. Mut 3

D. Mut 4

E. Mut 5

2. The triple mutant Mut5 and double mutant Mut4 exhibited thermostability improvement. What is the main difference between these mutants?

Enzyme SInv Mut 1 (P152 V) Mut2 (S85 V) Mut 3 (K153F) Mut 4 (S305 V and N463V) Mut 5 (S85 V, K153F and T271 V) Km (mM) 19t 0.6 14.33 0.7 23 0.6 36.03 0.9 19.72 -1.1 20.57 t 1.2 max. mmol min 0.3 0.36 0.27 0.24 0.3 0.32 Kcat/Km (S Immo 1) 13.15 20.35 10.8 12.67 13.36

Solution

1). A). Mut1

The value kcat/Km indicates the catalytic efficiency, in the given list, Mut1 has the higher catalytic efficiency than the wild-type enzyme. The higher Kcat and lower Km results in the higher catalytic efficiency of the enzyme. Km is the concentration of substrate at which half of the active sites are filled with the substrate molecules. If the enzyme has higher affinity towards the substrate, the Km is low and vice versa. For an enzyme, the kcat represents the number of chemical conversions (of substrate to product) that occur within a unit time period.