Enzymes — DU B. Sc. (Hons) Biochemistry Previous Year Question Papers

There are six questions. (a) Explain the following statements : 5x2 (i) A pure enzyme has maximum specific activity. (i7) V. max is directly proportional to enzyme concentration. (iti) Binding energy released upon enzyme-substrate binding lowers the activation energy of the reaction. (io) Prosthetic groups are tightly linked to enzymes. (v) Michaelis-Menten constant does not always reflect the affinity of the enzyme for the substrate. (b) Identify/Give an example öf the following : (i) Non-proteinaceous enzyme (ii) Enzyme used in ELISA : (iii) Enzyme responsible for methanol poisoning (v) Allosteric enzyme • • 2. (a) What is the significance of the following? (i) Lineweaver Burk plot is used for determining enzyme kinetic constants. . (ti) Some enzymes are synthesized as inactive precursors. (b) Chymotrypsin is an example of both acid-base and covalent catalysis. (e) To which class of enzymes the following belong? 3 (i) Cholesterol oxidase (ii) Lactate dehydrogenase (iii) Chymotrypsin. 3. (a) Differentiate between the following : 12 (i) Competitive and uncompetitive inhibition (i) Lock and key hypothesis and induced fit hypothesis (iii) Metal activated enzymes and metalloenzymes (iv) Single displacement and double displacement bisubstrate reaction. (6), Amoxicilin and Clavulinic acid are combined in a widely used pharmaceutical formulation used to treat bacterial infections. Explain the rationale behind this formulation. 3 (a) Identify the type of reactions in which the following coenzymes participate. Give an example of the reaction catalyzed. 9 (i) Thiamine pyrophosphate (TPP) (ii) Nicotinamide adenine dinucleotide (NAD) (6) What is the ratio of IS] to Km when velocity of an enzyme catalysed reaction is 90% of maximum velocity ? • 3 Briefly explain the allosteric regulation of ATCase enzyme. 3 5. (a) What are immobilized enzymes and how are they useful in biotechnology? 5 (6) Explain the applications of enzymes in the field of medicine and diagnostics with examples. 5 (c) Describe how the enzyme Glycogen phosphorylase is regulated by covalent modification. 5. 6. Write short notes on the following 5,5,5 (i) Coupled assays