Protein Engineering vol. 16 no. 12 pp. 1153-1157, 2003
© 2003 Oxford University Press
pH-responsive polymer-assisted refolding of urea- and organic solvent-denatured 
-chymotrypsin
Chemistry Department, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
1 To whom correspondence should be addressed. e-mail: mn_gupta{at}hotmail.com
A pH-responsive polymer Eudragit S-100 has been found to assist in correct folding of 
-chymotrypsin denatured with 8 M urea and 100 mM dithiothreitol at pH 8.2. The complete activity could be regained within 10 min during refolding. Both native and refolded enzymes showed emission of intrinsic fluorescence with 
max of 342 nm. Gel electrophoresis showed that the presence of Eudragit S-100 led to dissociation of multimers followed by the appearance of a band at the monomer position. The unfolding (by 8 M urea) and folding (assisted by the polymer) also led to complete renaturation of -chymotrypsin initially denatured by 90% dioxane. The implications of the data in recovery of enzyme activity from inclusion bodies and the interesting possibility in the in vivo context of reversing protein aggregation in amyloid-based diseases have been discussed.
Received June 17, 2003; revised September 26, 2003; accepted October 21, 2003