This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
[{'content': "Which of the following interactions contributes most to protein folding \nSelect and explain. \nA. Covalent Bond, B. Ionic interactions, C. Hydrophobic, D. Vander waal's interaction", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Protein folding: *The number of distinct combinations of phi and psi angles specifying potential conformations of even a relatively small-- 15 kDa--polypeptide is unbelievably vast, native conformation is specified in the primary sequence. In nature, protein folding takes place in a more orderly and guided fashion.*Protein folding generally occurs a stepwise process. In the first stage, as the newly synthesized polypeptide emerges from the ribosome, sho segments fold into secondary structural units that provide local regions of organized structure*the hydrophobic regions segregate into the interior of the protein away from the solvent, forming a "molten globule," a paially folded polypeptide*Cells employ auxiliary proteins to speed the process of folding and to guide it toward a productive conclusion*Chaperone proteins paicipate in the folding *The hsp70 (70 kDa heat shock protein) family of chaperones bind sho sequences of hydrophobic amino acids- shielding them from the solvent.*The hsp60 family of chaperones, sometimes called chaperonins, differ in sequence and structure from hsp70 and its homologs. Hsp60 acts later in the folding process, often together with an hsp70 chaperone. The central cavity of the donut-shaped hsp60 chaperone provides a sheltered environment in which a polypeptide can fold until all hydrophobic regions are buried in its interior, thus preempting any tendency toward aggregation.Ref: Harpers Biochemistry; 30th edition', 'role': 'assistant'}]