title: Interaction of weakly bound antibiotics neomycin and lincomycin with bovine and human serum albumin: biophysical approach.
abstract: The thermodynamics of interaction of neomycin and lincomycin with bovine serum albumin (BSA) and human serum albumin (HSA) has been studied using isothermal titration calorimetry (ITC), in combination with UV-visible, steady state and time resolved fluorescence spectroscopic measurements. Neomycin is observed to bind weakly to BSA and HSA whereas lincomycin did not show any evidence for binding with the native state of these proteins, rather it interacts in the presence of surfactants. The ITC results suggest 1 : 1 binding stoichiometry for neomycin in the studied temperature range. The values of the van't Hoff enthalpy do not agree with the calorimetric enthalpy in the case of neomycin, suggesting conformational changes in the protein upon ligand binding, as well as with the rise in the temperature. Experiments at different ionic strengths, and in the presence of tetrabutyl ammonium bromide and surfactants suggest the predominant involvement of electrostatic interactions in the complexation process of neomycin with BSA and HSA, and non-specific interaction behaviour of lincomycin with these proteins.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
authors.forename: Neelam
authors.initials: N
authors.lastname: Keswani
authors.forename: Sinjan
authors.initials: S
authors.lastname: Choudhary
authors.forename: Nand
authors.initials: N
authors.lastname: Kishore
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism*; D055592:Biophysical Phenomena / Q000187:drug effects; D002151:Calorimetry; D002417:Cattle; D006801:Humans; D008034:Lincomycin / Q000737:chemistry / Q000378:metabolism*; D009355:Neomycin / Q000737:chemistry / Q000378:metabolism*; D009994:Osmolar Concentration; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding / Q000187:drug effects; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012709:Serum Albumin / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents / Q000494:pharmacology; D013816:Thermodynamics; D013997:Time Factors; D017186:Titrimetry
chemical_list: D000900:Anti-Bacterial Agents; D000644:Quaternary Ammonium Compounds; D012709:Serum Albumin; D013501:Surface-Active Agents; D012710:Serum Albumin, Bovine; D008034:Lincomycin; C009405:tetrabutylammonium; D009355:Neomycin