title: Mutual induced fit in cyclodextrin-rocuronium complexes.
abstract: The binding of rocuronium bromide to 6-perdeoxy-6-per(4-carboxyphenyl)thio-gamma-cyclodextrin sodium salt, displays biphasic behaviour characteristic of the formation of a binary and 2 : 1 ternary guest-host complex in aqueous solution. Thermodynamic and structural data on this sequential complexation process can be rationalised within a single model involving switching of the conformational equilibria of both the rocuronium bromide and cyclodextrin molecules. Isothermal titration calorimetry (ITC), NMR and fluorescence experiments in solution, together with X-ray crystallography and molecular modelling, suggest that in order to induce encapsulation both rocuronium bromide and the modified cyclodextrin undergo conformational changes. Ring A of rocuronium bromide 'switches' from the more sterically encumbered chair to the sterically less demanding twist-boat, whilst the modified cyclodextrin "opens" its cavity to allow the steroid to enter. The recognition and mutual induced fit between cyclodextrin and steroid represents a classic example of dynamic host-guest chemistry.
authors.affiliation: Department of Chemistry, Glasgow University, Scotland, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Cooper
authors.forename: Margaret
authors.initials: M
authors.lastname: Nutley
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: MacLean
authors.forename: Ken
authors.initials: K
authors.lastname: Cameron
authors.forename: Lee
authors.initials: L
authors.lastname: Fielding
authors.forename: Jordi
authors.initials: J
authors.lastname: Mestres
authors.forename: Ronald
authors.initials: R
authors.lastname: Palin
mesh_terms: D000732:Androstanols / Q000737:chemistry*; D002151:Calorimetry; D003461:Crystallography; D003505:Cyclodextrins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009466:Neuromuscular Blocking Agents / Q000737:chemistry*; D000077123:Rocuronium; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000732:Androstanols; D003505:Cyclodextrins; D009466:Neuromuscular Blocking Agents; D000077123:Rocuronium