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Glycolipid Biosurfactants Activate, Dimerize, and Stabilize Thermomyces lanuginosus Lipase in a pH-Dependent Fashion

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  • Jens Kvist Madsen
  • ,
  • Jørn Døvling Kaspersen
  • ,
  • Camilla Bertel Andersen
  • ,
  • Jannik Nedergaard Pedersen
  • ,
  • Kell Kleiner Andersen, Agro Business Park A/S , Niels Pedersens Alle 2, DK-8660 Tjele, Denmark.
  • ,
  • Jan Skov Pedersen
  • Daniel E Otzen

We present a study of the interactions between the lipase from Thermomyces lanuginosus (TlL) and the two microbially produced biosurfactants (BSs), rhamnolipid (RL) and sophorolipid (SL). Both RL and SL are glycolipids; however, RL is anionic, while SL is a mixture of anionic and non-ionic species. We investigate the interactions of RL and SL with TlL at pH 6 and 8 and observe different effects at the two pH values. At pH 8, neither RL nor SL had any major effect on TlL stability or activity. At pH 6, in contrast, both surfactants increase TlL's thermal stability and fluorescence and activity measurements indicate interfacial activation of TlL, resulting in 3- and 6-fold improved activity in SL and RL, respectively. Nevertheless, isothermal titration calorimetry reveals binding of only a few BS molecules per lipase. Size-exclusion chromatography and small-angle X-ray scattering suggest formation of TlL dimers with binding of small amounts of either RL or SL at the dimeric interface, forming an elongated complex. We conclude that RL and SL are compatible with TlL and constitute promising green alternatives to traditional surfactants.

Original languageEnglish
Pages (from-to)4256-4268
Number of pages13
Publication statusPublished - 15 Aug 2017

    Research areas

  • Ascomycota, Enzyme Stability, Fungal Proteins, Glycolipids, Hot Temperature, Hydrogen-Ion Concentration, Lipase, Surface-Active Agents, X-Ray Diffraction, Journal Article

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