tailieunhanh - Báo cáo Y học: Effect of ibuprofen and warfarin on the allosteric properties of haem– human serum albumin A spectroscopic study

Department of Chemistry ‘IFM’, University of Torino, Italy; 2Department of Biology, University ‘Roma Tre’, Rome, Italy; 3Department of Structural and Functional Biology, University of Insubria, Italy Haem binding to human serum albumin (HSA) endows the protein with peculiar spectroscopic properties. Here, the effect of ibuprofen and warfarin on the spectroscopic properties of ferric haem –human serum albumin (ferric HSA–haem) and of ferrous nitrosylated haem –human serum albumin (ferrous HSA –haem-NO) is reported. Ferric HSA–haem is hexa-coordinated, the haem-iron atom being bonded to His105 and Tyr148. Upon drug binding to the warfarin primary site, the displacement of water molecules 2 buried in. | Eur. J. Biochem. 268 6214-6220 2001 FEBS 2001 Effect of ibuprofen and warfarin on the allosteric properties of haem-human serum albumin A spectroscopic study Simona Baroni1 Marco Mattu2 Alessandro Vannini2 Rita Cinollone2 Silvio Aime1 Paolo Ascenzi2 and Mauro Fasano3 1Department of Chemistry IFM University of Torino Italy department of Biology University Roma Tre Rome Italy department of Structural and Functional Biology University of Insubria Italy Haem binding to human serum albumin HSA endows the protein with peculiar spectroscopic properties. Here the effect of ibuprofen and warfarin on the spectroscopic properties of ferric haem-human serum albumin ferric HSA-haem and of ferrous nitrosylated haem-human serum albumin ferrous HSA-haem-NO is reported. Ferric HSA-haem is hexa-coordinated the haem-iron atom being bonded to His105 and Tyr148. Upon drug binding to the warfarin primary site the displacement of water molecules buried in close proximity to the haem binding pocket induces perturbation of the electronic absorbance properties of the chromophore without affecting the coordination number or the spin state of the haem-iron and the quenching of the 1H-NMR relaxivity. Values of Kd for ibuprofen and warfarin binding to the warfarin primary site of ferric HSA-haem corresponding to the ibuprofen secondary cleft are X 10 4 M and X 10 5 M respectively. The affinity of ibuprofen and warfarin for the warfarin primary cleft of ferric HSA-haem is lower than that reported for drug binding to haem-free HSA. Accordingly the Kd value for haem binding to HSA increases from X 10 8 M in the absence of drugs to X 10 7 M in the presence of ibuprofen and warfarin. Ferrous HSA-haem-NO is a five-coordinated haem-iron system. Drug binding to the warfarin primary site of ferrous HSA-haem-NO induces the transition towards the six-coordinated haem-iron species the haem-iron atom being bonded to His105. Remarkably the ibuprofen primary cleft appears to be