JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD Pharm. D I Year MEDICIAL BIOCHEMISTRY Previous Question Paper (September/October - 2021 - R08)

Energy-rich compounds are molecules that contain high-energy bonds, typically phosphate bonds, which release a significant amount of free energy upon hydrolysis. These compounds serve as the primary currency for energy transfer in biological systems. The most prominent example is Adenosine Triphosphate (ATP), which acts as the universal energy carrier. Other high-energy compounds include phosphoenolpyruvate, 1,3-bisphosphoglycerate, and creatine phosphate. Their high group-transfer potential allows them to drive endergonic reactions by coupling with exergonic hydrolysis.

Enzymes accelerate biochemical reactions by lowering the activation energy through the formation of an enzyme-substrate (ES) complex. The primary mechanisms include:

• Lock and Key Model: Proposes that the enzyme active site is structurally rigid and perfectly complementary to the specific substrate.
• Induced Fit Model: Suggests that the active site is flexible; the binding of the substrate induces a conformational change in the enzyme to achieve a precise fit, stabilizing the transition state.
• Catalytic Strategies: Enzymes utilize acid-base catalysis, covalent catalysis, and metal ion catalysis to facilitate bond breaking and formation within the active site.