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The changing face of SDS denaturation: Complexes of Thermomyces lanuginosus lipase with SDS at pH 4.0, 6.0 and 8.0

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  • Helena Østergaard Rasmussen
  • Daniel T Weltz Wollenberg, University of Southern Denmark, Novozymes A/S, Bagsværd
  • ,
  • Huabing Wang
  • ,
  • Kell K Andersen
  • ,
  • Cristiano L P Oliveira
  • ,
  • Christian Isak Jørgensen, Novozymes A/S, Bagsværd
  • ,
  • Thomas J D Jørgensen, University of Southern Denmark
  • ,
  • Daniel E Otzen
  • Jan Skov Pedersen

HYPOTHESIS: Lipases are widely used in the detergent industry and must withstand harsh conditions involving both anionic and zwitterionic surfactants at alkaline pH. Thermomyces lanuginosus lipase (TlL) is often used and stays active at high concentrations of the anionic surfactant sodium dodecyl sulfate (SDS) at pH 8.0, but is sensitive to SDS at pH 6.0 and below. We propose that enhanced stability at pH 8.0 results from a structurally distinct complex formation with SDS.

EXPERIMENTS: We use small-angle X-ray scattering (SAXS) to elucidate structures of TlL:SDS at pH 4.0, 6.0, and 8.0 and further investigate the complexes at pH 8.0 using hydrogen/deuterium exchange mass spectrometry (HDX-MS).

FINDINGS: At pH 4.0, large dense aggregates are formed at low [SDS], which become gradually less dense at higher [SDS], resulting in a core-shell structure. At pH 6.0, SDS induces a TlL dimer and forms a hemi-micelle along the side of the dimer. At higher [SDS], TlL adopts a core-shell structure. At pH 8.0, TlL forms a dimer with a SDS hemi-micelle but avoids a core-shell structure and maintains activity. Three helices are identified as SDS anchor points. This study provides important structural insight into the stability of TlL towards SDS under alkaline conditions.

Original languageEnglish
JournalJournal of Colloid and Interface Science
Volume614
Pages (from-to)214-232
Number of pages19
ISSN0021-9797
DOIs
Publication statusE-pub ahead of print - 10 Jan 2022

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