5-(2-Aminoethyl)homocysteine 6367-70-0 BUTYRIC ACID, 2-AMINO-4-((2-AMINOETHYL)THIO)-, HYDROCHLORIDE, L- L-2-Amino-4-((2-aminoethyl)thio)butyric acid hydrochloride S-2-Aminoethyl-homocysteine monohydrochloride USAF B-4