234 C. B. ANFINSEN [13 



high extinction coefficient of this material.) These findings strongly suggest 

 that the substrate, ribonucleic acid, is capable of refolding the protein in 

 spite of the presence of 8m urea and that the structural configuration respon- 

 sible for catalytic activity is unchanged by this agent under the conditions 

 of assay. 



Table 6 



SOME PHYSICAL PROPERTIES OF RIBONUCLEASE AND 

 MODIFIED RIBONUCLEASE 



The concentration of the proteins was 2-5-2-7 g./l. for spectrophotometric readings, 

 25-30 g./l. for Polarimetrie, and 14-15 g./l. for viscometric measurements. All measure- 

 ments were carried out at pH 6-7. 



* See Yang and Doty (1957). 



