20662-32-2 2936-69-8 4099-35-8 617-71-0 63905-31-7 Aminoethylcysteine NSC 241277 S-(2-Aminoethyl)-L-cysteine S-2-Aminoethyl cysteine S-beta-Aminoethyl cysteine Thiosine gamma-Thia-lys gamma-Thialysine