THE ULTRAVIOLET ABSORPTION SPECTRUM OF PEPSIN.

The ultraviolet absorption spectrum of Northrop's pure crystalline pepsin has been determined. The curve of calculated molecular extinction coefficients is given. There is noted a general resemblance of the absorption curve for pepsin to that for urease and tyrosine; the absorption band is maximum at 2750-2800 A.micro., minimum near 2500. A slight hump on either side of the peak of the extinction curve may be significant.