S-Benzyl-L-cysteine, C10H13NO2S, contains two molecules in the asymmetric u
nit, both of which are zwitterions. They differ principally in terms of mol
ecular conformation about their C alpha -C beta bonds; one is approximately
anti, the other gauche for the N-C-C-S grouping. The N-H . . .O hydrogen-b
onding scheme has been elucidated.