The molecule is a peptide zwitterion obtained by transfer of a proton from the carboxy to the amino group of bacilysin; major species at pH 7.3. It is a tautomer of a bacilysin.
(2S)-2-[[(2S)-2-azaniumylpropanoyl]amino]-3-[(1R,2S,6R)-5-oxo-7-oxabicyclo[4.1.0]heptan-2-yl]propanoate