Biochemistry 4th Edition by Christopher Mathews,Kensal van Holde, Dean Appling, Spencer Anthony Cahill

Exercise 12

Note that some of these problems refer to information presented in the Tools of Biochemistry 5A-D.
A researcher has isolated an oligopeptide of unknown sequence and unknown amino acid composition. All attempts to sequence it by Edman degradation fail; the reaction just will not go.
(a) Suggest two quite different possible explanations for the problem.
(b) Suggest an experiment that will at least distinguish between these two.