(S)-2-((S)-2-((tert-Butoxycarbonyl)amino)-3-methylbutanamido)propanoic acid

(S)-3-Amino-4-((carboxymethyl)amino)-4-oxobutanoic acid

(S)-2-((S)-2-Amino-3-carboxypropanamido)succinic acid

(S)-2-((S)-2-Aminopropanamido)-3-methylbutanoic acid

(S)-2-((S)-2-Aminopropanamido)-3-hydroxypropanoic acid

(S)-2-((S)-2-Aminopropanamido)-3-(1H-imidazol-5-yl)propanoic acid

(R)-2-((S)-2-Aminopropanamido)propanoic acid

(S)-2-(2-Aminoacetamido)-3-phenylpropanoic acid

(2S,4R)-4-Hydroxy-1-((S)-pyrrolidine-2-carbonyl)pyrrolidine-2-carboxylic acid

(S)-2-Amino-5-(((R)-1-((carboxymethyl)amino)-1-oxo-3-sulfopropan-2-yl)amino)-5-oxopentanoic acid