Why are optically active compounds abundant in nature?

Question

Enantiomers have most physical properties exactly same, which makes them hard to seperate from one another. Due to large amounts of physical similarities and chemical similarities (when dealing with optical non active compounds) anyone will assume that if I eat any one of enantiomers of some compound I will get same amount of energy and they will perform exact same task in my body. Given that many optically active compounds are extracted from nature, why do organisms go through pain of separating enantiomers for their consumption? Why do optical isomers are found in nature that are hard to separate in a lab?

Answer 1

The main difference between nature and lab is that nature and biological systems use enzymes and proteins. Within these enzymes and proteins, the binding site has a certain chirality based on the folding of the amino acids. Plants and biological systems break down specific chiralities based on how well they bind to the pocket and undergo reactivity. A way to think about this is you are either naturally right handed or left handed without being directed into a preference. The same thing occurs with enzymes, they are naturally given a handedness based on how they were made regardless of what we want them to do. In the lab we have slowly developed methods to separate enantiomers using a technique known as chiral chromatography, however you are correct in that the bulk properties of the enantiomers are the same, which is hard to separate based on pKa, solubility, normal chromatography.