The only difference between HbA and HbS in a single amino acid in the beta chain, where Glu of HbA is mutated to Biology The only difference between HbA and HbS in a single amino acid in the beta chain, where Glu of HbA is mutated to A. Gln B. Asp C. Asn D. Phe E. Val Answer: E Share this Share on FacebookTweet on TwitterPlus on Google+