The following are the statements about pyruvate kinase (PK).

A. ATP is an allosteric inhibitor of PK.

B. Fructose 1, 6 biphosphate is an activator of PK.

C. ADP is an allosteric inhibitor of PK.

D. Alanine is an allosteric modulator of PK.

Which of the above statement (s) are true?

• A, B, and C

• A, B, and D

• B, C, and D

• Only A

The exact backbone dihedral angles in a folded protein can be obtained by

• deconvolution of its circular dichroism spectra obtained at different pH and temperature.

• estimating the number of protons that exchange with deuterium on treating the protein with D₂O.

• forming fibres of the protein and analyzing the fiber diffraction pattern.

• analysis of the crystal structure of the protein obtained by X-ray diffraction at high resolutions.

Which one of the following statements is correct?

• In all L-amino acids, only the C^α carbon atom is chiral.

• Deoxyribose is optically inactive.

• The specific rotation of sucrose will be the sum of the specific rotations of D-glucose and D-fructose.

• Phosphatidyl choline isolated from biological membranes is optically active.

Which one of the following would contribute to intrinsic fluorescence to a protein?

• aromatic amino acids

• disulfide bonds

• charged amino acids

• branched chain amino acids

Which isotope below is best suited for metabolic labelling of glyceraldehyde-3-phospho-dehydrogenase?

• ¹⁴C

• ¹²⁵I

• ³²P

• ¹³¹I

Coupling of the reaction centers of oxidative phosphorylation is achieved by which one of the following?

• Making a complex of all four reaction centers.

• Locating all four complexes in the inner membrane.

• Ubiquinones and cytochrome C.

• Pumping of protons

Enzymes accelerate a reaction by which one of the following strategies?

• Decreasing energy required to form the transition state.

• Increasing kinetic energy of the substrate.

• Increasing the free energy difference between the substrate and the product.

• Increasing the turn over number of enzymes.

A cell line deficient in the salvage pathway for nucleotide biosynthesis was fed with medium containing ¹⁵N labeled amino acids. Purines were then extracted. Treatment with which one of the following amino acids is likely to produce ¹⁵N labelled purines?

• Aspartic acid

• Glycine

• Glutamine

• Aspartamine

The ionic strength of a 0.2 M Na₂HPO₄ solution will be

• 0.2 M

• 0.4 M

• 0.6 M

• 0.8 M

From statements on protein structure and interactions detailed below, indicate the correct statement.

• The concentration of a tryptophan-containing protein can be determined by monitoring the fluorescence spectrum of the protein.

• A peptide with an equal number of Glu and Lys amino acids can show multiple charged species in its electrospray ionization mass spectrum.

• The circular dichroism spectrum of a protein shows predominantly helical conformation. Analysis of its two dimensional NMR spectrum shows predominantly β-structure.

• Binding constant can be determined by two interacting molecules by the technique of surface plasma resonance only if there is strong hydrophobic interactions between them.