JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD Pharm. D I Year MEDICIAL BIOCHEMISTRY Previous Question Paper (October - 2020 - R08)

ATP (Adenosine Triphosphate) consists of an adenine base, a ribose sugar, and three phosphate groups linked by high-energy phosphoanhydride bonds. Cyclic AMP (cAMP) consists of an adenine base, a ribose sugar, and a single phosphate group linked to both the 3' and 5' carbons of the ribose, forming a cyclic structure.

Biological significance: ATP serves as the primary energy currency of the cell, providing energy for muscle contraction, active transport, and biosynthetic reactions through the hydrolysis of its terminal phosphate bonds. cAMP acts as a crucial secondary messenger in signal transduction pathways, mediating the effects of hormones like adrenaline and glucagon by activating protein kinases to regulate intracellular metabolic processes.

Enzymes are biological catalysts, typically proteins, that accelerate chemical reactions by lowering the activation energy without being consumed in the process. Factors affecting their activity include:

• Substrate Concentration: Increasing substrate concentration increases reaction velocity until it reaches a maximum velocity (Vmax) where all enzyme active sites are saturated.
• Temperature: Enzyme activity increases with temperature up to an optimum point; beyond this, thermal denaturation occurs, leading to a loss of catalytic function.
• pH: Each enzyme has an optimal pH range; extreme deviations cause ionization changes in amino acid residues at the active site, disrupting substrate binding.
• Enzyme Concentration: The rate of reaction is directly proportional to the enzyme concentration, provided substrate is in excess.
• Inhibitors: Competitive inhibitors compete with the substrate for the active site, while non-competitive inhibitors bind elsewhere to alter the enzyme's conformation.