an S-substituted L-cysteine = a thiol + 2-aminoprop-2-enoate
an s-substituted l-cysteine = a thiol + 2-aminoprop-2-enoate
an S-substituted L-cysteine = a thiol + 2-aminoprop-2-enoate
an s-substituted l-cysteine = a thiol + 2-aminoprop-2-enoate