In selecting amino acids to be used in the diet,is the optical activity of the acid important?explain your answer

Answer 1

The body largely has enzyme pathways that can work with L-isomers only.
<<Bryan Douglas Crawford
University of New Brunswick
I think the prevalence of L-amino acids in biological systems is a quirk of our evolutionary history; there's no reason D-amino acids wouldn't work chemically, but once early life forms started building proteins out of L-amino acids, L-amino acids became abundant an it became selectively advantageous to use L-amino acids because then you could use the amino acids you obtained by eating someone else. It's a matter of compatibility; if you use D-amino acids, you have to build them all from scratch, because you're not going to find them in your environment. As long as you use L-amino acids, you don't even need to maintain the de novo synthetic pathways; you can just eat something that has those pathways (hence the 'essential' dietary amino acids).>>