(6R,7R)-3-[(4-Carbamoylpyridin-1-ium-1-yl)methyl]-8-oxo-7-[[(2R)-2-phenyl-2-sulfoacetyl]amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate;Cefsulodin; 

(2S)-1-(3-Mercapto-2-methylpropionyl)-L-proline;Captopril; (S,S)-1-(D-3-Mercapto-2-methyl-1-oxopropyl)-L-proline; (s,s)-1-(d-3-mercapto-2-methyl-1-oxopropyl)-l-proline;(2s)-1-(3-mercapto-2-methylpropionyl)-l-proline;