The folding pathways of some proteins require two enzymes that catalyze isomerization reactions such as,

a) Peptide prolyl isomerase (PPI)  catalyzes the elimination of folding intermediates with inappropriate disulfide cross-links

b) Protein disulfide isomerase (PDI) enzyme that catalyzes the interchange, or shuffling, of disulfide bonds until the bonds of the native conformation are formed

c) Peptide prolyl cis-trans isomerase (PPI) catalyzes the interconversion of the cis and trans isomers of Proline residue peptide bonds

d) Peptide prolyl isomerase (PPI) can be a fast step in the folding of proteins that contain some Pro peptide bonds in the cis conformation

Which of the following combinations is correct about protein folding pathways?

#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.

#Question id: 792

#Part-B Specialized Branches in Biotechnology

Which arm of the tRNA can act as a structural recognition feature?

#Question id: 825

#Part-A Aptitude & General Biotechnology

Which of the following amino acids are responsible for the formation of intrinsically disordered proteins?

#Question id: 19228

#Part-A Aptitude & General Biotechnology

#Question id: 14152

#Part-B Specialized Branches in Biotechnology