What do L- and D- in chirality stand for?
Karin and Jerry are wrong, and Scott is correct. The capital D and L (typographically they should be small capitals) use the Fischer-Rosanoff convention to specify the absolute configuration of a compound, usually sugars and amino acids. The D isomer is the one that degrades to (+)-glyceraldehyde, and the L isomer is the one that degrades to (-)-glyceraldehyde. Effectively that means that the bottom chiral carbon in the Fischer projection has its OH group (or NH2 group in amino acids) on the right in the D isomer and on the left in the L isomer. Specification of an optical rotation is done using (+) or d (lower case Italic d) for the dextrorotatory isomer, and (-) or l (lower case italic ell) for the levorotatory isomer. Dextro is toward the right (clockwise) and levo is toward the left (CCW). For example, D-(-)-arabinose is levorotatory, but it degrades to the dextrorotatory isomer of glyceraldehyde.
