#Question id: 713
#Part-B Specialized Branches in Biotechnology
Which of the following polypeptides is most likely to form an α helix?
#Question id: 715
#Part-B Specialized Branches in Biotechnology
A protein is made up of 200 amino acids with alpha helix region containing 100 amino acid residues and 80 amino acids making antiparallel beta sheet and rest 20 amino acids in extended form. What will be the total length of this protein?
#Question id: 717
#Part-B Specialized Branches in Biotechnology
What is Φ & Ψ angles for collagen triple helix?
#Question id: 719
#Part-B Specialized Branches in Biotechnology
Suppose that a 40-residue segment of a protein folds into a two-stranded antiparallel β structure with a 4-residue hairpin turn. What is the longest dimension of this motif?
#Question id: 721
#Part-B Specialized Branches in Biotechnology
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 -11000 deg cm2 dmol-1 in the presence of 6M urea. Initially it was observed that tile values of mean residue ellipticity at 220 nm ([θ]220) are -36000, and +4000 deg cm2 dmol-1 for α-helix, and random coil conformations of this polypeptide. The percentage of the polypeptide in α-helix conformation is:
#Question id: 723
#Part-B Specialized Branches in Biotechnology
Common structural elements in proteins such as α-helices or β-sheets are characterized by uniformly repeating, energetically favorable main chain conformations which additionally exhibit a completely saturated hydrogen-bonding network of the main chain NH and CO groups. Although polyproline or polyglycine type II helices (PPII or PGII ) are frequently found in proteins, they are not considered as equivalent secondary structure elements. Which of the following statements are correct about PP and PGs.
A. PGII -like helices form hexagonal bundles which appear to fulfill the criterion of a (largely) saturated hydrogen-bonding network of the main-chain groups
B. main chain NH and CO groups of the central PGII -helix are saturated by either intra- or intermolecular hydrogen-bonds, resulting in a self-contained hydrogen-bonding network
C. The formation of the right-handed PPI helix is possible only with proline residues because of the required cis conformation.
D. PPII helices seem to be stabilized by main chain-water hydrogen bonds (in the absence of main chain- main chain H-bonds), and tend to have a regular pattern of hydrogen bonds with water. After this, it is not surprising, that PPII helices are found mostly on the protein surface.