Question

When purified RNAse-A is incubated with 8M Urea and the thiol reducer mercapto-ethanol, it unfolds completely and looses all activity. Upon removal of the urea and mercapto-ethanol we get active RNAse-A protein back in a test tube. a) What is the important conclusion that we can draw from this observation in a test tube? b) To what extent is this observation relevant for what takes place in a cell?

Answer 1

a)The important conclusion that we can draw from this observation in the test tube is that the process of protein refolding is possible in vitro when urea and mercaptoethanol is reduced.Thus, RNAase could regain its biological activity forming RNAse -A protein back in the test tube.

b) In vivo or we can say in a cell, the protein refolding takes place much faster than in vitro i.e usually in seconds and this might be via activity of enzymes such as protein disulfide isomerase that functions to catalyse correct disulfide bond formation.