Given below are two statements: Statement I: Increase in temperature of a reaction mixture up to an optimum value increases the rate of enzyme reaction as it enhances the rate of collision between the substrate and enzyme active sites Statement II: Increase in the temperature beyond an optimum value breaks the non-covalent bonds in enzyme first and thereby reaction velocity is decreased In the light of the above statements, choose the most appropriate answer from the options given below
Step 1: Understanding the Concept:
Enzyme thermal kinetics reflect the interplay between kinetic activation energy ($Q_{10} \approx 2$) and conformational thermal denaturation. Step 2: Detailed Explanation:
1. Statement I: As temperature rises up to the optimum temperature ($T_{\text{opt}} \approx 37-40^\circ\text{C}$ in mammals), increased thermal kinetic energy accelerates molecular motion, increasing the frequency and energy of productive collisions between substrate and catalytic active sites (doubling rate per $10^\circ\text{C}$ rise). Hence, Statement I is true. 2. Statement II: Beyond the optimum temperature, excessive thermal vibrational energy disrupts weak non-covalent interactions (hydrogen bonds, ionic bonds, hydrophobic forces) stabilizing the enzyme's native tertiary conformation, causing active site denaturation and loss of catalytic velocity. Hence, Statement II is true. Step 3: Final Answer:
Thus, Both Statement I and Statement II are true, matching option (A).
