title: The tertiary amine local anesthetic dibucaine binds to the membrane skeletal protein spectrin.
abstract: The quinoline-based tertiary amine dibucaine has been shown to bind the membrane skeletal protein spectrin with a dissociation constant of 3.5x10(-5) M at 25 degrees C. Such binding is detected by monitoring the quenching of the tryptophan fluorescence intensity with increasing concentrations of dibucaine only and not with the benzene-based local anesthetics procaine, tetracaine and lidocaine. Binding of dibucaine also indicated changes in the tertiary structure of spectrin indicated by a circular dichroism spectrum in the near-UV region due to absorption of the aromatic side chains. The thermodynamic parameters associated with the binding indicated the interaction of dibucaine and spectrin to be enthalpy-driven and insensitive to an increase in the ionic strength of the buffer.
authors.affiliation: Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, 700064, Calcutta, India.
authors.forename: Mousumi
authors.initials: M
authors.lastname: Mondal
authors.forename: Abhijit
authors.initials: A
authors.lastname: Chakrabarti
mesh_terms: D000588:Amines / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002942:Circular Dichroism; D003992:Dibucaine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000378:metabolism; D006041:Goats; D006358:Hot Temperature; D007477:Ions; D007700:Kinetics; D008012:Lidocaine / Q000494:pharmacology; D011343:Procaine / Q000494:pharmacology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013049:Spectrin / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013748:Tetracaine / Q000494:pharmacology; D013816:Thermodynamics; D014364:Tryptophan / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000588:Amines; D000779:Anesthetics, Local; D007477:Ions; D013748:Tetracaine; D013049:Spectrin; D011343:Procaine; D014364:Tryptophan; D008012:Lidocaine; D003992:Dibucaine