Answer to Question #260426 in Cell Biology for hayrunisa

Question

Protein structure is determined solely by a protein’s amino acid sequence. Should a genetically engineered protein in which the original order of all amino acids is reversed have the same structure as the original protein?

Answer 1

No. It would not have the same or even a similar structure, because the peptide bond has a polarity.

Looking at two sequential amino acids in a polypeptide chain, the amino acid that is closer to the N terminal end contributes the carboxyl group and the other amino acid contributes the amino group to the peptide bond that links the two. Changing their order would put the side chains into a different position with respect to the peptide backbone and therefore change their chemical environment.