Why do all organic molecules have the same chirality or handedness?

1 Answer
Mar 7, 2016

Well, they don't. Molecules of BIOLOGICAL ORIGIN tend to have a specific handedness.


When you open a bag of white sugar, and look at all the beautiful crystals, it is a sobering thought to realize that not only is this material chemically pure (i.e. it corresponds to the formula of sucrose, whatever this is), it is ALSO optically pure (and IT'S CHEAP TOO!). Sucrose has a specific handedness, and its optical isomer (unavailable from sugar cane or beet) would not be metabolized. Why not? Because the enzymes that catalyze sugar metabolism are themselves handed, and will only function on the one optical isomer.

Of course, sucrose derives from a biological source. Proteins, which also derive from a biological source, also tend to exhibit the one particular handedness.

In the laboratory, both organic chemists and inorganic chemists work to isolate materials of both optical antipodes. It must be a very demanding job.