about aa chirality Normally, the a-carbon is the only chiral center with several exceptions. There are ways to determine the d-and L-forms of amino acids .Only the L-amino acids have been found in proteins D-isomers have been found only in small peptides of bacteria cell walls and in some peptide antibiotics). The correlation of structure(or configuration) with optical rotation is very complex and has not been successful to date!(i.e, the D- and L-signs do not tell anything about their optical rotation!)About AA chirality： •Normally, the -carbon is the only chiral center with several exceptions. •There are ways to determine the D- and L-forms of amino acids. •Only the L-amino acids have been found in proteins (D-isomers have been found only in small peptides of bacteria cell walls and in some peptide antibiotics). •The correlation of structure (or configuration) with optical rotation is very complex and has not been successful to date! (i.e., the D- and L-signs do not tell anything about their optical rotation!)