Structural changes in collagen. The action of alkalis and acids in the conversion of collagen into eucollagen

substrate during the reaction; wavelength, 284 mu (or within the range 284-290 mu); initial substrate concentration, within the range 0 1-0 3 mg./ml.; slit width as narrow as possible. The final decision on slit width will depend on the conditions of the experiment and the sensitivity and stability of the spectrophotometer. The most important factor is that it should remain constant throughout a set of mneasurements; SUMMARY 1. A spectrophotometric assay of bovine ribo- nuclease has been developed based on the change in ultraviolet-absorption spectrum resulting from the hydrolysis of cytidine 2':3'-phosphate.