138 



C. B. ANFINSEN AND R. R. REDFIELD 



60 60 



ml efjiuent volume 



Fig. 9. Chromatography of 10 mg. samples of native and pepsin-digested ribo- 

 nuclease on IRC-50 columns, 9 x 30 mm. Eluting buffer, phosphate, 0.2 M, pH 6.45. 

 Digestion conditions: ribonuclease 0.92%; pepsin (xArmour crystallized ca. 0.002%; 

 37°C, pH 1.8. Remaining ribonuclease activity (I): Curve A, 100%; B, 60% (5 min); 

 C, 40% (10 min); D, 15% (16 min). Solid points, enzyme activity. Open circles, pro- 

 tein concentration. (The peak appearing at 18-19 effluent ml. is a ninhydrin-negative 

 artefact, uniformly seen with this preparation of resin.) 



course, quite beyond consideration at the present time. It is of interest, how- 

 ever, that the alkali-catalyzed rupture of tyrosine hydroxyl hydrogen bonding 

 in ribonuclease indicated by the spectrophotometric experiments of Tanford, 

 Hauenstein and Rands (1955), also has been found to parallel the loss in enzy- 

 matic activity (Anfinsen and Tritch, unpublished data). 



The next figure (Fig. 13) shows the results of a crude attempt to schematize 

 and summarize some of the approaches to the basis of ribonuclease function. It 



