Protein Structure and Function: Advanced Concepts and Biomedical Applications — DU B. Sc. (Hons) Biomedical Previous Year Question Papers

Give illustrations, biochemical reactions, and examples wherever required. Q.1a). Give one word/term for the following statements (5) (i) Proteins that lack a stable three-dimensional structure under physiological conditions. (ii) A protein structural motif characterized by periodic hydrophobic amino acids enabling dimer formation, coupled with a basic region responsible for DNA binding. (iii) The pH at which a molecule carries no net electrical charge, resulting in minimal mobility in an electric field. (iv) Enzymes used in laboratory detection systems such as ELISA (v) Fibrous protein providing tensile strength to skin, hair, and nails. Q.1b) Indicate whether each statement is true or false, with a brief justification. (10) (i) The terms protein and polypeptide are not interchangeable. (ii) There is an increase in the synthesis of chaperones when the temperature is raised. (iii) Sanger's reagent reacts specifically with the N-terminal anino acid of a protein. (iv) Therapeutic proteins act with high apecificity toward their targets. (v) His, Ser, and Asn are likely to be found on the solventexposed surface of a protein. Q2. Write Short Notes on any three of the following: (i) Zn-finger motif with function (ii) Christian Anfinsen' s experiment (iv) Types, properties, and applications of Industrial Enzymes Q3. Elaborate on the differences between: (i) Oxygen binding curves of Hemoglobin and Myoglobin (ii) Hydrophobic collapse and Chaperone-assisted folding (iv) Industrial enzymes in detergents (v) Diagnostic biomarkers and Prognostic biomarkers Q.4 (a) What intermolecular forces in proteins are affected by: (i) Heat; (ii) pH; (iii) Q. 4 Q. 4 (b) Before sequencing a protein with disulfide-linked polypeptides, reduction and alkylation are required. Explain the biochemical basis of this step. (5) (c) Discuss the principle and clinical significance of enzyme replacement therapy with one suitable example. (6) Q. 5 Q.5 Q.5 (a) At a partial pressure ofonygen (p02), hemoglobin is 75% saturated. If the total hemoglobin concentration is 8 mM, calculate: (5) (i) The concentration of oxygen-bound hemoglobin (ii) The average number of 02 molecules bound per hemoglobin molecule (b) A protein has Tin = 60°C. After mutation, Tin becomes 50°C. Calculate °/o decrease in stability. If AG folding = -30 kJ/mol, what does this indicate about spontaneity? ( 5 ) (c) A protein of200 anino acids is digested with trypsin, generating multiple peptide fragments. Out of these, 5 peptide fragments are identified by mass spectrometry, covering a total of 60 amino acids of the protein sequence. Answer the following: (i) Calculate the sequence coverage (%) (ii) Comment on the confidence of protein identification based on this coverage ( 5 )