This problem concerns the interpretation of N-terminal analysis results. Remember, N-terminal analysis is just that, no sequencing information is provided.

a) N-terminal analysis of a pure protein yielded three different amino acids. Concisely discuss two possible interpretations of this result and suggest a way to clearly distinguish between those interpretations.

b) While analyzing a different pure protein, N-terminal analysis yielded no amino acids. Concisely discuss two possible interpretations of this result and suggest a way to clearly distinguish or confirm the possible interpretations.