35. Which of the following atomic nuclei cannot be probed by nuclear magnetic resonance spectroscopy? (A) ¹H (B) ³¹P (C) ¹⁸O (D) ¹⁵N Nuclei That Can and Cannot Be Studied […]
Tag: CSIR NET Life Science Previous Year Questions on METHODS IN BIOLOGY
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CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Near-UV Circular Dichroism of Hemoglobin
34. Haemoglobin has characteristic circular dichroism (CD) peaks in the far-UV, near UV and Soret regions. Contribution to near-UV CD comes entirely from (A) Aromatic amino acid residues. (B) Heme […]
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Identifying a Disulfide-Bridged β-Hairpin Peptide
33. Following observations are made regarding a peptide sequence. – The peptide is inert to Ellman’s reagent. However, on reacting with β-mercaptoethanol, the peptide gives a positive Ellman’s test. – […]
![32. Poly-L-lysine exists in pure α-helix, β-sheet and random coiled conformation depending upon the solvent conditions. The values of mean residue ellipticity at 220 nm ([Θ]₂₂₀) are −35,700, −13,800 and +3,900 deg cm² dmol⁻¹ for α-helical, β-sheet and random coil conformations of this polypeptide, respectively. The polypeptide exists in α-helix conformation at pH 10.8 and 25°C. Addition of urea leads to a two-state transition between α-helix and random coil conformation. It has been observed that [Θ]₂₂₂ of the polypeptide is −14,800 deg cm² dmol⁻¹ in the presence of 6 M urea. The percentage of the polypeptide in α-helix conformation is: (A) 37 (B) 41 (C) 47 (D) 50](https://www.letstalkacademy.com/wp-content/uploads/2026/07/32.jpg)
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Calculating Alpha-Helix Percentage
32. Poly-L-lysine exists in pure α-helix, β-sheet and random coiled conformation depending upon the solvent conditions. The values of mean residue ellipticity at 220 nm ([Θ]₂₂₀) are −35,700, −13,800 and […]
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Identifying Helical Conformation of a Polymer
31. A polymer is synthesized from an achiral amino acid. Conformation of the polymer can be investigated by the following techniques. A. Fibre diffraction B. Nuclear magnetic resonance spectroscopy C. […]
![30. At 25°C values of [Θ]₂₂₂, the mean residue ellipticity at 222 nm, are −33,000 and −3,000 deg cm² dmol⁻¹ for a polypeptide existing in α-helical (α) and β-structure (β), respectively. If this polypeptide undergoes a two-state heat-induced α → β transition, and a value of [Θ]₂₂₂ = −18,000 deg cm² dmol⁻¹ is observed at 60°C, then this observation leads to the conclusion that the α helix conversion to β-structure: (A) 40% (B) 50% (C) 55% (D) 60%](https://www.letstalkacademy.com/wp-content/uploads/2026/07/30.jpg)
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Alpha-Helix to Beta-Sheet Conversion
30. At 25°C values of [Θ]₂₂₂, the mean residue ellipticity at 222 nm, are −33,000 and −3,000 deg cm² dmol⁻¹ for a polypeptide existing in α-helical (α) and β-structure (β), […]
![29. A protein polypeptide chain exists in α-helical conformation in a solvent and it has a value of −30,000 deg cm² dmol⁻¹ for the mean residue ellipticity at 222 nm ([Θ]₂₂₂) in the temperature range 20–50°C. On raising the temperature above 50°C, [Θ]₂₂₂ increases and reaches a value of −2,000 deg cm² dmol⁻¹ at 70°C and the value of [Θ]₂₂₂ remains unchanged above 70°C. The observed value of [Θ]₂₂₂ is −14,000 deg cm² dmol⁻¹ at 60°C. If one assumes that the heat-induced denaturation is a two-state process, the fraction of α-helix at 60°C is (A) 0.40 (B) 0.43 (C) 0.50 (D) 0.57](https://www.letstalkacademy.com/wp-content/uploads/2026/07/29.jpg)
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Fraction of Alpha-Helix from Circular Dichroism Ellipticity
29. A protein polypeptide chain exists in α-helical conformation in a solvent and it has a value of −30,000 deg cm² dmol⁻¹ for the mean residue ellipticity at 222 nm […]
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Alpha-Helix Stability During Cooling in Circular Dichroism
28. A 26-residue peptide composed of alanine and leucine shows a circular dichroism (CD) spectrum characteristic of α-helix at 50°C in 5 mM phosphate buffer at pH 7.4. Deconvolution of […]
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
How Circular Dichroism Identifies Beta-Sheet Structure
27. Which one of the following statements is correct? (1) Electrospray ionization mass spectrum of a compound can be obtained only if it has a net positive charge at pH […]
CSIR NET Life Science Previous Year Questions and Solutions Spectroscopy
Why Are Thermophilic Proteins More Stable
26. Two homologous proteins were isolated from a psychrophile (P) and a thermophile (T). The purified proteins were subjected to denaturation, protease digestion and circular dichroism (CD). Following observations were […]
