Biochemistry
Among the following bonds where rotation is not allowed in a peptide chains? (1) ψ (2) ω (3) x (4) φ In a peptide chain, rotation is restricted due to partial double-bond character of certain bonds. Let’s analyze each option: 1. ψ (Psi) angle – Rotation Allowed ✅ This is the Cα–C bond (between the … Read more
Arrange the three residues, glycine, phenylalanine and proline, in the decreasing order of backbone flexibility (1) Gly > Phe > Pro (2) Pro > Gly > Phe (3) Phe > Pro > Gly (4) It is not possible to comment Backbone flexibility in amino acids depends on the torsional freedom of the main chain (Φ, … Read more
In a polypeptide chain, a cis-to-trans rearrangement of two consecutive proline residues can be achieved by rotating the: (1) O angle to 10° (2) w angle to 180° (3) Ψ angle to 0° (4) x angle to 60° In a polypeptide chain, cis-to-trans isomerization primarily involves rotation around the peptide bond (ω angle). ω (omega) … Read more
The measured values of main chain torsion angles of a residue in a polypeptide has values (Φ=+50, Ψ=+60). What type of secondary structure is it most likely to be present in?
(1) Left-handed a-helix
(2) Right-handed a-helix
(3) Type II ẞ-turn
(4) Parallel B-sheet
The φ and ψ values of a 310-helix is composed of all D. amino acids will mainly occupy which quadrant in the Ramachandran plot? (1) upper left (2) upper right (3) lower left (4) lower right For a typical 3₁₀-helix composed of L-amino acids, the dihedral angles are approximately: These values place the helix in … Read more
In peptides the values of dihedral angle phi (D) is based on rotation around (1) N-Ca bond (2) Ca -C’ bond (3) C’-N bond (4) N-H bond The phi (φ) angle in peptides is defined as the dihedral angle around the N–Cα bond. This angle is measured between the plane formed by the C’ (of … Read more
phi, psi angles of a peptide segment adopting alpha helical conformation would be around (1)-78, +59 (2) +49,+26 (3)-57,-78 (4)-60,-40 The alpha helix is characterized by backbone dihedral angles (φ and ψ) that typically fall within a narrow range. For a right-handed alpha helix, the commonly accepted values are approximately: Among the options provided: Thus, … Read more