title: Spectroscopic characterization of copper(II) binding to the immunosuppressive drug mycophenolic acid.
abstract: Mycophenolic acid (MPA) is a drug that has found widespread use as an immunosuppressive agent which limits rejection of transplanted organs. Optimal use of this drug is hampered by gastrointestinal side effects which can range in severity. One mechanism by which MPA causes gastropathy may involve a direct interaction between the drug and gastric phospholipids. To combat this interaction we have investigated the potential of MPA to coordinate Cu(II), a metal which has been used to inhibit gastropathy associated with use of the NSAID indomethacin. Using a range of spectroscopic techniques we show that Cu(II) is coordinated to two MPA molecules via carboxylates and, at low pH, water ligands. The copper complex formed is stable in solution as assessed by mass spectrometry and 1H NMR diffusion experiments. Competition studies with glycine and albumin indicate that the copper-MPA complex will release Cu(II) to amino acids and proteins thereby allowing free MPA to be transported to its site of action. Transfer to serum albumin proceeds via a Cu(MPA)(albumin) ternary complex. These results raise the possibility that copper complexes of MPA may be useful in a therapeutic situation.
authors.affiliation: Centre for Metals in Biology, School of Molecular and Microbial Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia. christopheredward.jones@uq.edu.au
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Jones
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Taylor
authors.forename: Alastair G
authors.initials: AG
authors.lastname: McEwan
authors.forename: Graeme R
authors.initials: GR
authors.lastname: Hanson
mesh_terms: D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005998:Glycine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007166:Immunosuppressive Agents / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D015394:Molecular Structure; D009173:Mycophenolic Acid / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry
chemical_list: D007166:Immunosuppressive Agents; D008024:Ligands; D012710:Serum Albumin, Bovine; D003300:Copper; D009173:Mycophenolic Acid; D005998:Glycine