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The following statements were made to describe a typical collagen structure. A. Collagen has a triple-helical domain structure which consists of three distinct α-chains. B. The collagen triple helix is stabilized by isoprenyl bonds. C. Each α-chain has a left-handed polyproline ll-type helix. D. Each α-chain is composed of multiple triplet sequences of Gly-Y-Z in which Y is commonly proline and Z is usually hydroxyproline. Which one of the following options has all correct statements?

CSIR PYQ Biochemistry-Conformation of Proteins

Collagen: Triple Helix, Amino Acid Composition, and Stability

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March 25, 2025
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The following statements were made to describe a typical collagen structure. A. Collagen has a triple-helical domain structure which consists of three distinct α-chains. B. The collagen triple helix is […]

Following are statements on ß-turns: A. All the 20 coded amino acids have equal propensity to form ß -turns. B. Pro cannot occur in ß-turns. C. Pro-Gly sequence strongly favours ß-turns. D. In Asn-Gly ß-turns, Asn can have positive ϕ,Ψ values. Choose the combination with all correct statements

CSIR PYQ Biochemistry-Conformation of Proteins

Beta-Turns in Proteins: Structure

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March 25, 2025
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23. Following are statements on ß-turns: A. All the 20 coded amino acids have equal propensity to form ß -turns. B. Pro cannot occur in ß-turns. C. Pro-Gly sequence strongly […]

In a 30-residue peptide, the dihedral angles φ/Ψ have been determined by one or more methods. When their values are examined in the Ramachandran plot, it is (1) not possible for φ/ Ψ values to be distributed in the helical as well as beta sheet region. (2) possible that the φ/ Ψ values are all in the helical region although circular dichroism spectral studies indicate beta sheet conformation. (3) possible to conclude that the peptide is composed of entirely D-amino acids. (4) not possible to conclude if the peptide is entirely helical or entirely in beta sheet conformation.

CSIR PYQ Biochemistry-Conformation of Proteins

Ramachandran Plot and Protein Conformation Analysis

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March 25, 2025
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In a 30-residue peptide, the dihedral angles φ/Ψ have been determined by one or more methods. When their values are examined in the Ramachandran plot, it is (1) not possible […]

$The exact backbone dihedral angles in a folded protein can be obtained by (1) deconvolution of its circular dichroism spectra obtained at different pH and temperature (2) estimating the number of protons that exchange with deuterium on treating the protein with D2O (3) forming fibres of the protein and analyzing the fibre diffraction pattern (4) analysis of the crystal structure of the protein obtained by X-ray diffraction at high resolutions$

CSIR PYQ Biochemistry-Conformation of Proteins

Determining Backbone Dihedral Angles in Folded Proteins

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March 25, 2025
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The exact backbone dihedral angles in a folded protein can be obtained by (1) deconvolution of its circular dichroism spectra obtained at different pH and temperature (2) estimating the number […]

The following are four statements on the peptides/proteins conformation: A. Glycine has a largest area of conformationally allowed space in the Ramachandran plot of Φ and Ψ B. A 20-residue peptide that is acetylated at the N-terminus and amidated at the C- terminus has Φ = -600 (±5), Ψ = -300(±5) for all the residues. It can be concluded that conformation of the peptide is helix-turn-strand C. The allowed values of Φ, Ψ for amino acids in a protein are not valid for short peptide D. A peptide Acetyl-A1 – A2 -A3 -A4-CONH2 (A-A4 are amino acids) adopts well defined ß-turn. The dihedral angles of A2 and A3 determined the type of ß- turn Choose the combination of correct statements.

CSIR PYQ Biochemistry-Conformation of Proteins

Protein Structure and Ramachandran Plot Analysis

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March 25, 2025
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The following are four statements on the peptides/proteins conformation: A. Glycine has a largest area of conformationally allowed space in the Ramachandran plot of Φ and Ψ B. A 20-residue […]

Given below are statements related to protein structures: A. The dihedral angles of an amino acid X in Acetyl-x- N-Methyl amide in the Ramachandran plot, occur in very small but equal areas in the left and right quadrants. It can be concluded that X is not one of the 20-coded amino acids. B. The dihedral angles of a 20-residue peptide are represented in the Ramachandran plot. It is possible to conclude that the peptide does not have a proline. C. Two proteins can have a similar fold even if they do not share significant similarity in their primary structure. D. On denaturation of a protein by urea, the interactions that would be disrupted are ionic bonds and van der Waal’s interaction but not disulfide bonds. Choose the combination with ALL CORRECT answers:

CSIR PYQ Biochemistry-Conformation of Proteins

Protein Structures: Ramachandran Plot and Structural Stability

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March 25, 2025
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Given below are statements related to protein structures: A. The dihedral angles of an amino acid X in Acetyl-x- N-Methyl amide in the Ramachandran plot, occur in very small but […]

The hemagglutinin protein in influenza virus contains a long α-helix, with 53 residues. Which of the following correctly describes the attributes of this α helix? (1) The length is 75.6 Å, 14 turns, total of 102 Hydrogen bonds (2) The length is 106 Å, 14 turns, total of 106 Hydrogen bonds (3) The length is 75.6Å, 14 turns, total of 104 Hydrogen bonds (4) The length is 75.6Å, 10 turns, total of 102 Hydrogen bonds

CSIR PYQ Biochemistry-Conformation of Proteins

Structure of Hemagglutinin α-Helix in Influenza Virus

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March 25, 2025
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The hemagglutinin protein in influenza virus contains a long α-helix, with 53 residues. Which of the following correctly describes the attributes of this α helix? (1) The length is 75.6 […]

How many hydrogen bonds involving the backbone CO and NH can be observed in an a-helix consisting of 15 amino acid residues? (1) 10 (2) 11 (3) 12 (4) 13

CSIR PYQ Biochemistry-Conformation of Proteins

Hydrogen Bonding in an α-Helix of 15 Amino Acids

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March 25, 2025
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How many hydrogen bonds involving the backbone CO and NH can be observed in an a-helix consisting of 15 amino acid residues? (1) 10 (2) 11 (3) 12 (4) 13 […]

An α-helix in a peptide or protein is characterized by hydrogen bonds and characteristic dihedral angles. Choose the right combination. (1) Hydrogen bonding between the amide CO of residue i and amide NH of residue i + 4. Dihedral angles in the region φ = -500, Ψ = -600 (2) Hydrogen bonding between the amide NH of residue i and amide CO of residue i + 4. Dihedral angles in the region of φ = -500, Ψ = -60. (3) Hydrogen bonding between the amide CO of residue i and amide NH of residue i + 4. Dihedral angles in the region of φ = -500, Ψ = +60. (4) Hydrogen bonding between the amide CO of residue i and amide NH of residue 1 + 3. Dihedral angles in the region of φ = -500, Ψ = -60

CSIR PYQ Biochemistry-Conformation of Proteins

Dihedral Angles and Hydrogen Bonding in α-Helices

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March 25, 2025
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An α-helix in a peptide or protein is characterized by hydrogen bonds and characteristic dihedral angles. Choose the right combination. (1) Hydrogen bonding between the amide CO of residue i […]