title: Protein surface-assisted enhancement in the binding affinity of an inhibitor for recombinant human carbonic anhydrase-II.
abstract: We elaborate on a novel strategy for enhancing the binding affinity of an active-site directed inhibitor by attaching a tether group, designed to interact with the surface-exposed histidine residue(s) of enzymes. In this approach, we have utilized the recombinant form of human carbonic anhydrase-II (hCA-II) as the enzyme source and benzenesulfonamide and its derivatives as inhibitors. The steady-state kinetic and the ligand binding data revealed that the attachment of iminodiacetate (IDA)-Cu(2+) to benzenesulfonamide (via a triethylene glycol spacer) enhanced its binding affinity for hCA-II by about 40-fold. No energetic contribution of either IDA or triethylene glycol spacer was found (at least in the ground state of the enzyme-inhibitor complex) when Cu(2+) was stripped off from the tether group-conjugated sulfonamide derivative. Arguments are presented that the overall strategy of enhancing the binding affinities of known inhibitors by attaching the IDA-Cu(2+) groups to interact with the surface-exposed histidine residues will find a general application in designing the isozyme-specific inhibitors as potential drugs.
authors.affiliation: Contribution from the Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, ND 58105, USA.
authors.forename: Abir L
authors.initials: AL
authors.lastname: Banerjee
authors.forename: Michael
authors.initials: M
authors.lastname: Swanson
authors.forename: Bidhan C
authors.initials: BC
authors.lastname: Roy
authors.forename: Xiao
authors.initials: X
authors.lastname: Jia
authors.forename: Manas K
authors.initials: MK
authors.lastname: Haldar
authors.forename: Sanku
authors.initials: S
authors.lastname: Mallik
authors.forename: D K
authors.initials: DK
authors.lastname: Srivastava
mesh_terms: D001665:Binding Sites; D024402:Carbonic Anhydrase II / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D002257:Carbonic Anhydrase Inhibitors / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D018360:Crystallography, X-Ray; D006801:Humans; D007098:Imino Acids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D008958:Models, Molecular; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013449:Sulfonamides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013499:Surface Properties; D000096926:Benzenesulfonamides
chemical_list: D024402:Carbonic Anhydrase II; D002257:Carbonic Anhydrase Inhibitors; D007098:Imino Acids; D011994:Recombinant Proteins; D013449:Sulfonamides; D000096926:Benzenesulfonamides; C008109:iminodiacetic acid