The molecule is puromycin monoprotonated at the amino nitrogen. It is the predominant species at pH 7.3. It is a conjugate acid of a puromycin.
[(2S)-1-[[(2S,3S,4R,5R)-5-[6-(dimethylamino)purin-9-yl]-4-hydroxy-2-(hydroxymethyl)oxolan-3-yl]amino]-3-(4-methoxyphenyl)-1-oxopropan-2-yl]azanium