How can I draw the structures of the two enantiomers of alanine?
Draw them as Fischer projections.
The easiest way is to draw them as Fischer projections.
The general formula for an amino acid is RCH(NH₂)COOH.
In alanine, R = CH₃.
You draw the Fischer projection for an amino acid in the same way as for a carbohydrate.
The main chain is vertical, with C-1 at the top. If the NH₂ group is on the left, you have an L-amino acid. If the NH₂ group is on the right, you have an R-amino acid.
So the two structures of alanine are
Note that L-alanine has the (