#Question id: 882
#Unit 1. Molecules and their Interaction Relevant to Biology
Choose correct statements about thermophilic proteins
I. The proteins found in thermophilic species are much more stable than their mesophilic counterparts.
II. All thermostable proteins have such a high incidence of salt bridges
III. the most important of which are an increased size of the protein’s hydrophobic core, an increased size of the interface between its domains and/or subunits, and a more tightly packed core as evidenced by a reduced surface-to-volume ratio.
IV. Several of these thermostable enzymes have a superabundance of salt bridges on their surfaces.
#Question id: 883
#Unit 1. Molecules and their Interaction Relevant to Biology
The “core autophagy machinery” controls the initiation and growth of the autophagosome and has been divided into three main protein groups:
i. A-ATG9, B-TOR, C-PI(3) Complex
ii. A- ATG9, B-PI(3) Complex, C-TOR
iii. The TOR kinase complex acts as a negative regulator of autophagy
iv. The TOR kinase complex acts as a positive regulator of autophagy
#Question id: 884
#Unit 1. Molecules and their Interaction Relevant to Biology
The hydrogen bonds, which are central features of protein structures, then what is the reason behind it makes only minor contributions to protein stability?
#Question id: 885
#Unit 1. Molecules and their Interaction Relevant to Biology
The half-lives of many cytoplasmic proteins vary with the identities of their N-terminal residues via the N-end rule.
a) Proteins with the “destabilizing” N-terminal residues contain Asp, Arg, Leu, Lys, and Phe with their half-lives > 2 to 3 hours
b) Proteins with the “destabilizing” N-terminal residues with their half-lives of only 2 to 3 minutes contain; Asp, Arg, Leu, Lys, and Phe
c) Proteins contain Ala, Gly, Met, Ser, Thr, and Val have half-lives of >10 hours are stabilizing N-terminal residue in prokaryotes
d) Those with the “stabilizing” N-terminal residues Ala, Gly, Met, Ser, Thr, and Val have half-lives of >20 hours in eukaryotes
Which of the following is correct?
#Question id: 886
#Unit 1. Molecules and their Interaction Relevant to Biology
An experiment of Anfinsen on ribonuclease A (RNase A) showed that proteins can be denatured reversibly by 2-mercaptoethanol and 8 M urea. The protein must therefore renature spontaneously;
a) Remove mercaptoethanol and then removal of the urea
b) Removal of the mercaptoethanol allows the protein to re-form disulfide bonds in the presence of oxygen and then removal of the urea
c) Removal of the denaturant (urea) and reductant (mercaptoethanol) allows the protein to renature and re-form disulfide bonds in the absence of oxygen
d) Adding a small amount of mercaptoethanol to the scrambled protein in the absence of O2 catalyzes its conversion to the active enzyme
Which one of the following steps will leads to regaining of the full activity of ribonuclease A (RNase A)
#Question id: 887
#Unit 1. Molecules and their Interaction Relevant to Biology
Polypeptides fold rapidly by a stepwise process, how does the polypeptide chain arrive at its native conformation?