title: Interaction between lactate dehydrogenase and Tween 80 in aqueous solution.
abstract: OBJECTIVE
  The weak aqueous interaction between the protein lactate dehydrogenase (LDH) and the nonionic surfactant Tween 80 has been investigated, because weak protein-amphiphile interactions are of significant importance in pharmaceutical formulations, but are experimentally hard to determine. The system LDH/sodium dodecyl sulphate (SDS) was used as reference because SDS, by its strong protein binding, denatures LDH completely.
  
  
  METHODS
  Fluorescence spectroscopy with pyrene and 1,3-bis(lphenyl)propane (P3P) as probes, intrinsic protein fluorescence and NMR spectroscopy have been used.
  
  
  RESULTS
  The fluorescence probe pyrene monitors a weak Tween-LDH interaction, detectable below the critical micelle concentration of ordinary Tween micelles. The microviscosity probe P3P shows a surfactant-induced denaturation in the case of LDH/SDS but not in the case of LDH/Tween 80. Intrinsic LDH fluorescence verifies this behavior. Pulsed-gradient spin-echo NMR was also used to verify the weak LDH-Tween 80 interaction. CONCLUSIONS. A weak interaction between LDH and Tween 80 occurs at hydrophobic zones of the protein, but it is not strong enough to denature LDH. The experimental outline used here provides a useful approach for mapping the very weak protein-amphiphile interactions often present in pharmaceutical formulations.
authors.affiliation: Department of Pharmacy, Uppsala University, Uppsala Biomedical Center, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Hillgren
authors.forename: Hans
authors.initials: H
authors.lastname: Evertsson
authors.forename: Maggie
authors.initials: M
authors.lastname: Aldén
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning / Q000379:methods; D004347:Drug Interactions; D007770:L-Lactate Dehydrogenase / Q000737:chemistry* / Q000493:pharmacokinetics; D019999:Pharmaceutical Solutions / Q000737:chemistry / Q000493:pharmacokinetics; D011136:Polysorbates / Q000737:chemistry* / Q000493:pharmacokinetics; D011721:Pyrenes / Q000493:pharmacokinetics; D011817:Rabbits; D013050:Spectrometry, Fluorescence / Q000379:methods; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D019999:Pharmaceutical Solutions; D011136:Polysorbates; D011721:Pyrenes; D014867:Water; C030984:pyrene; D007770:L-Lactate Dehydrogenase