The molecule is an amino acid zwitterion resulting from a transfer of a proton from the carboxy group to the amino group of nocardicin G; major species at pH 7.3. It is a tautomer of a nocardicin G.
(2R)-2-[(3S)-3-[[(2R)-2-azaniumyl-2-(4-hydroxyphenyl)acetyl]amino]-2-oxoazetidin-1-yl]-2-(4-hydroxyphenyl)acetate