Question

FP3 is 227 amino acids long. If 62 amino acids are the same between FP1 and FP3, what percentage of amino acids in FP3 match corresponding amino acids in FP1? Show your work

Answer 1

Since each of the 20 amino acids is chemically distinct and each can, in principle, occur at any position in a protein chain, there are 20 × 20 × 20 × 20 = 160,000 different possible polypeptide chains four amino acids long, or 20n different possible polypeptide chains n amino acids long.