Biochemistry 4th Edition by Reginald Garrett, Charles Grisham

Exercise 2

Using site-directed mutants to understand an enzyme mechanism
In this chapter, the experiment in which Craik and Rutter replaced Asp 102 with Asn in trypsin (reducing activity 10,000-fold) was discussed.
a. On the basis of your knowledge of the catalytic triad structure in trypsin, suggest a structure for the "uncatalytic triad" of Asn-His-Ser in this mutant enzyme.
b. Explain why the structure you have proposed explains the reduced activity of the mutant trypsin.
c. See the original journal articles (Sprang, et al., 1987. Science 237:905-909 and Craik, et al., 1987. Science 237:909-13) to see what Craik and Rutter's answer to this question was.