title: Chemical-structural properties of tetracycline antibiotics. 4. Ring A tautomerism involving the protonated amide substituent as observed in the crystal structure of alpha-6-deoxyoxytetracycline hydrohalides.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D004318:Doxycycline; D006860:Hydrogen Bonding; D007536:Isomerism; D014961:X-Ray Diffraction
chemical_list: D004318:Doxycycline