Adsorption and mobility of a lipase at a hydrophobic surface in the presence of surfactants
2006 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, no 13, 5810-1817 p.Article in journal (Refereed) Published
With the aim of being able to manipulate the processes involved in interfacial catalysis, we have studied the effects of a mixture of nonionic/anionic surfactants, C12E6/LAS (1: 2 mol %), on the adsorption and surface mobility of a lipase obtained from Thermomyces lanuginosus (TLL). Surface plasmon resonance (SPR) and ellipsometry were used to analyze the competitive adsorption process between surfactants and TLL onto hydrophobic model surfaces intended to mimic an oily substrate for the lipase. We obtained the surface diffusion coefficient of a fluorescently labeled TLL variant on silica silanized with octadecyltrichlorosilane (OTS) by fluorescence recovery after photobleaching (FRAP) on a confocal laser scanning microscope. By means of ellipsometry we calibrated the fluorescence intensity with the surface density of the lipase. The TLL diffusion was measured at different surface densities of the enzyme and at two time intervals after coadsorption with different concentrations of C12E6/LAS. The surfactant concentrations were chosen to represent concentrations below the critical micelle concentration (CMC), in the CMC region, and above the CMC. The apparent TLL surface diffusion was extrapolated to infinite surface dilution, D-0. We found that the presence of surfactants strongly modulated the surface mobility of TLL: with D-0 = 0.8 x 10(-11) cm(2)/s without surfactants and D-0 = 13.1 x 10(-11) cm(2)/s with surfactants above the CMC. The increase in lipase mobility on passing the CMC was also accompanied by a 2- fold increase in the mobile fraction of TLL. SPR analysis revealed that surface bound TLL was displaced by C12E6/LAS in a concentration-dependent manner, suggesting that the observed increase in surface mobility imparts bulk-mediated diffusion and so-called rebinding of TLL to the surface. Our combined results on lipase/surfactant competitive adsorption and lipase surface mobility show how surfactants may play an important role in regulating interfacial catalysis from physiological digestion to technical applications such as detergency.
Place, publisher, year, edition, pages
2006. Vol. 22, no 13, 5810-1817 p.
Adsorption; Hydrophobicity; Mathematical models; Physiology; Surface active agents; Surface tension; Interfacial catalysis; Oily substrate; Surface plasmon resonance (SPR; Thermomyces lanuginosus; Enzymes; immobilized enzyme; surfactant; triacylglycerol lipase; adsorption; article; Ascomycetes; chemical structure; chemistry; enzymology; fluorescence recovery after photobleaching; hydrophobicity; surface plasmon resonance; surface property; surface tension; Adsorption; Ascomycota; Enzymes, Immobilized; Fluorescence Recovery After Photobleaching; Hydrophobicity; Lipase; Models, Molecular; Surface Plasmon Resonance; Surface Properties; Surface Tension; Surface-Active Agents
IdentifiersURN: urn:nbn:se:kth:diva-6930DOI: 10.1021/la0531244ISI: 000238217000048ScopusID: 2-s2.0-33745760732OAI: oai:DiVA.org:kth-6930DiVA: diva2:11781
QC 201008182007-03-272007-03-272010-12-21Bibliographically approved