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Lipase surface diffusion studied by Fluorescence Recovery After Photobleaching
KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
Novozymes A/S, Bagsvaerd.
KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.ORCID iD: 0000-0003-0578-4003
YKI, Institute for Surface Chemistry, Stockholm.
2005 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 25, 11949-11956 p.Article in journal (Refereed) Published
Abstract [en]

We have analyzed surface diffusion properties of a variant of Thermomyces lanuginosa lipase (TLL) on hydrophilic silica and silica methylated with dichlorodimethylsilane (DDS) or octadecyltrichlorosilane (OTS). For this study a novel method for analysis of diffusion on solid surfaces was developed. The method is based on fluorescence recovery after photobleaching using confocal microscopy. When a rectangular area of the sample was photobleached, fluorescence recovery could be analyzed as one-dimensional diffusion, resulting in simplified mathematical expressions for fitting the data. The method was initially tested by measuring bovine serum albumin diffusion on glass, which led to a diffusion coefficient in good correspondence to earlier reports. For the analysis of TLL diffusion, ellipsometry data of TLL adsorption were used to calibrate fluorescence intensity to surface density of lipase, enabling measurements of the diffusion coefficient at different surface densities. The average diffusion coefficient was calculated in two time intervals after adsorption. Mobile fraction and diffusion coefficient were lowest on the OTS surface, when extrapolated to infinite surface dilution. Moreover, the diffusion rate decreased with time on the hydrophobic surfaces. Our observations can be explained by the surface dependence on the distribution of orientations and conformations of adsorbed TLL, where the transition from the closed to the catalytically active open and more hydrophobic structure is important.

Place, publisher, year, edition, pages
2005. Vol. 21, no 25, 11949-11956 p.
Keyword [en]
Adsorption; Bleaching; Enzymes; Fluorescence; Hydrophobicity; Photochemical reactions; Silanes; Surface chemistry; Dichlorodimethylsilane (DDS); Octadecyltrichlorosilane (OTS); Surface diffusion; Thermomyces lanuginosa lipase (TLL); Diffusion
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-6929DOI: 10.1021/la051773+ISI: 000233730200061Scopus ID: 2-s2.0-29444450721OAI: oai:DiVA.org:kth-6929DiVA: diva2:11780
Note
QC 20100818Available from: 2007-03-27 Created: 2007-03-27 Last updated: 2010-08-18Bibliographically approved
In thesis
1. Dynamics of Enzymes at Interfaces: Lipase adsorption and mobility on solid surfaces
Open this publication in new window or tab >>Dynamics of Enzymes at Interfaces: Lipase adsorption and mobility on solid surfaces
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis aimed to give more insight in the dynamics of enzymes at interfaces. The adsorption and mobility of adsorbed proteins can e.g. give a better understanding of structure-function properties of interfacially active enzymes. Studied enzyme was the lipase from Thermomyces lanuginosus (TLL).

Adsorption of TLL to surfaces of different hydrophobicity was studied by Dual Polarization Interferometry (DPI), Surface Plasmon Resonance (SPR) and ellipsometry. It was found that TLL had highest affinity and adsorbed to largest adsorbed amount on a hydrophobic, C18 terminated surface. Moreover, activity studies of adsorbed TLL suggested that a larger fraction of the lipases were orientated with the active site facing the surface on hydrophobic surfaces.

Mobility of adsorbed enzymes was studied by means of Fluorescence Recovery After Photobleaching (FRAP) with Confocal Laser Scanning Microscopy (CLSM). CLSM was also used as a tool to image the role of TLL in the detergency of lipids from single cotton fibers. The TLL surface mobility was measured on model surfaces of different hydrophobicity. The rate of TLL surface diffusion was strongly dependent on the surface density of lipase, which was explained by sterical hindrance and intermolecular repulsion. The diffusion was both lowest and decreased as a function of time after adsorption on the most hydrophobic surface. This was thought to be due to a larger fraction of adsorbed TLL oriented with the active site towards the hydrophobic surface and that this fraction increased as a function of time.

The presence of surfactants affected the TLL mobility on hydrophobic surfaces. The diffusion increased more than tenfold when TLL was coadsorbed with C12E6/LAS above the critical micellar concentration (cmc) of the surfactant. This was thought to be due to a surfactant induced desorption-rebinding mechanism of TLL. Total Internal Reflection Fluorescence Correlation Spectroscopy (TIR-FCS) supported this theory and was implemented as a technique to quantify kinetic processes of protein-surfactant interactions at surfaces.

The surface mobility of TLL was higher on a trimyristin substrate surface compared to the model hydrophobic surface. Single particle tracing of lipases could be performed by conjugation of TLL to Quantum Dots (QDs). The microscopic behavior of QD-lipases on trimyristin suggested that the enzyme operated in two different modes on the surface, which gave the trajectories of single lipase molecules a “bead on a string” appearance.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. 57 p.
Series
Trita-FYS, ISSN 0280-316X ; 2007:20
Keyword
biophysics, surface chemistry, diffusion, enzymes, lipases, adsorption, mobility
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-4319 (URN)978-91-7178-604-3 (ISBN)
Public defence
2007-04-23, FB53, AlbaNova, Roslagstullsbacken 21, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100818Available from: 2007-03-27 Created: 2007-03-27 Last updated: 2010-08-18Bibliographically approved

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