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Moses ME, Lund PM, Bohr SSR, Iversen JF, Kæstel-Hansen J, Kallenbach AS, Iversen L, Christensen SM, Hatzakis NS. Single-Molecule Study of Thermomyces lanuginosus Lipase in a Detergency Application System Reveals Diffusion Pattern Remodeling by Surfactants and Calcium. ACS APPLIED MATERIALS & INTERFACES 2021; 13:33704-33712. [PMID: 34235926 DOI: 10.1021/acsami.1c08809] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Lipases comprise one of the major enzyme classes in biotechnology with applications within, e.g., baking, brewing, biocatalysis, and the detergent industry. Understanding the mechanisms of lipase function and regulation is therefore important to facilitate the optimization of their function by protein engineering. Advances in single-molecule studies in model systems have provided deep mechanistic insights on lipase function, such as the existence of functional states, their dependence on regulatory cues, and their correlation to activity. However, it is unclear how these observations translate to enzyme behavior in applied settings. Here, single-molecule tracking of individual Thermomyces lanuginosus lipase (TLL) enzymes in a detergency application system allowed real-time direct observation of spatiotemporal localization, and thus diffusional behavior, of TLL enzymes on a lard substrate. Parallelized imaging of thousands of individual enzymes allowed us to observe directly the existence and quantify the abundance and interconversion kinetics between three diffusional states that we recently provided evidence to correlate with function. We observe redistribution of the enzyme's diffusional pattern at the lipid-water interface as well as variations in binding efficiency in response to surfactants and calcium, demonstrating that detergency effectors can drive the sampling of lipase functional states. Our single-molecule results combined with ensemble activity assays and enzyme surface binding efficiency readouts allowed us to deconvolute how application conditions can significantly alter protein functional dynamics and/or surface binding, both of which underpin enzyme performance. We anticipate that our results will inspire further efforts to decipher and integrate the dynamic nature of lipases, and other enzymes, in the design of new biotechnological solutions.
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Affiliation(s)
- Matias E Moses
- Novozymes A/S, Biologiens Vej 2, DK-2800 Kgs. Lyngby, Denmark
- Department of Chemistry & Nano-science Center, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Philip M Lund
- Novozymes A/S, Biologiens Vej 2, DK-2800 Kgs. Lyngby, Denmark
- Department of Chemistry & Nano-science Center, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Søren S-R Bohr
- Department of Chemistry & Nano-science Center, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Josephine F Iversen
- Department of Chemistry & Nano-science Center, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Jacob Kæstel-Hansen
- Department of Chemistry & Nano-science Center, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Amalie S Kallenbach
- Department of Chemistry & Nano-science Center, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Lars Iversen
- Novozymes A/S, Biologiens Vej 2, DK-2800 Kgs. Lyngby, Denmark
| | | | - Nikos S Hatzakis
- Department of Chemistry & Nano-science Center, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
- Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen N, Denmark
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Bohr SSR, Lund PM, Kallenbach AS, Pinholt H, Thomsen J, Iversen L, Svendsen A, Christensen SM, Hatzakis NS. Direct observation of Thermomyces lanuginosus lipase diffusional states by Single Particle Tracking and their remodeling by mutations and inhibition. Sci Rep 2019; 9:16169. [PMID: 31700110 PMCID: PMC6838188 DOI: 10.1038/s41598-019-52539-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 10/08/2019] [Indexed: 12/11/2022] Open
Abstract
Lipases are interfacially activated enzymes that catalyze the hydrolysis of ester bonds and constitute prime candidates for industrial and biotechnological applications ranging from detergent industry, to chiral organic synthesis. As a result, there is an incentive to understand the mechanisms underlying lipase activity at the molecular level, so as to be able to design new lipase variants with tailor-made functionalities. Our understanding of lipase function primarily relies on bulk assay averaging the behavior of a high number of enzymes masking structural dynamics and functional heterogeneities. Recent advances in single molecule techniques based on fluorogenic substrate analogues revealed the existence of lipase functional states, and furthermore so how they are remodeled by regulatory cues. Single particle studies of lipases on the other hand directly observed diffusional heterogeneities and suggested lipases to operate in two different modes. Here to decipher how mutations in the lid region controls Thermomyces lanuginosus lipase (TLL) diffusion and function we employed a Single Particle Tracking (SPT) assay to directly observe the spatiotemporal localization of TLL and rationally designed mutants on native substrate surfaces. Parallel imaging of thousands of individual TLL enzymes and HMM analysis allowed us to observe and quantify the diffusion, abundance and microscopic transition rates between three linearly interconverting diffusional states for each lipase. We proposed a model that correlate diffusion with function that allowed us to predict that lipase regulation, via mutations in lid region or product inhibition, primarily operates via biasing transitions to the active states.
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Affiliation(s)
- Søren S-R Bohr
- Department of Chemistry & Nanoscience Center, Thorvaldsensvej 40, University of Copenhagen, Frederiksberg C, 1871, Denmark
- NovoNordisk center for protein research, Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Philip M Lund
- Department of Chemistry & Nanoscience Center, Thorvaldsensvej 40, University of Copenhagen, Frederiksberg C, 1871, Denmark
- NovoNordisk center for protein research, Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Amalie S Kallenbach
- Department of Chemistry & Nanoscience Center, Thorvaldsensvej 40, University of Copenhagen, Frederiksberg C, 1871, Denmark
- NovoNordisk center for protein research, Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Henrik Pinholt
- Department of Chemistry & Nanoscience Center, Thorvaldsensvej 40, University of Copenhagen, Frederiksberg C, 1871, Denmark
- NovoNordisk center for protein research, Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Johannes Thomsen
- Department of Chemistry & Nanoscience Center, Thorvaldsensvej 40, University of Copenhagen, Frederiksberg C, 1871, Denmark
- NovoNordisk center for protein research, Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Lars Iversen
- Novozymes A/S, Krogshøjsvej 36, DK 2880, Bagværd, Denmark
| | - Allan Svendsen
- Novozymes A/S, Krogshøjsvej 36, DK 2880, Bagværd, Denmark
| | | | - Nikos S Hatzakis
- Department of Chemistry & Nanoscience Center, Thorvaldsensvej 40, University of Copenhagen, Frederiksberg C, 1871, Denmark.
- NovoNordisk center for protein research, Novo Nordisk Foundation Centre for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.
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Nabavi Zadeh PS, Zezzi do Valle Gomes M, Abrahamsson M, Palmqvist AEC, Åkerman B. Measuring viscosity inside mesoporous silica using protein-bound molecular rotor probe. Phys Chem Chem Phys 2018; 20:23202-23213. [DOI: 10.1039/c8cp01063c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluorescence spectroscopy of protein-bound molecular rotors Cy3 and Cy5 is used to monitor the effective viscosity inside the pores of two types of mesoporous silica (SBA-15 and MCF) with pore diameters between 8.9 and 33 nm.
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Affiliation(s)
- Pegah S. Nabavi Zadeh
- Chalmers University of Technology
- Department of Chemistry and Chemical Engineering
- Physical Chemistry
- SE-41296 Gothenburg
- Sweden
| | - Milene Zezzi do Valle Gomes
- Chalmers University of Technology
- Department of Chemistry and Chemical Engineering
- Applied Chemistry
- SE-41296 Gothenburg
- Sweden
| | - Maria Abrahamsson
- Chalmers University of Technology
- Department of Chemistry and Chemical Engineering
- Physical Chemistry
- SE-41296 Gothenburg
- Sweden
| | - Anders E. C. Palmqvist
- Chalmers University of Technology
- Department of Chemistry and Chemical Engineering
- Applied Chemistry
- SE-41296 Gothenburg
- Sweden
| | - Björn Åkerman
- Chalmers University of Technology
- Department of Chemistry and Chemical Engineering
- Physical Chemistry
- SE-41296 Gothenburg
- Sweden
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Joyce P, Kempson I, Prestidge CA. Orientating lipase molecules through surface chemical control for enhanced activity: A QCM-D and ToF-SIMS investigation. Colloids Surf B Biointerfaces 2016; 142:173-181. [DOI: 10.1016/j.colsurfb.2016.02.059] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/23/2016] [Accepted: 02/25/2016] [Indexed: 11/16/2022]
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Cui X, Liu X, Tatton AS, Brown SP, Ye H, Marsh A. Nanodiamond promotes surfactant-mediated triglyceride removal from a hydrophobic surface at or below room temperature. ACS APPLIED MATERIALS & INTERFACES 2012; 4:3225-32. [PMID: 22676238 DOI: 10.1021/am300560z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We demonstrate that ca. 5 nm nanodiamond particles dramatically improve triglyceride lipid removal from a hydrophobic surface at room temperature using either anionic or nonionic surfactants. We prepare nanodiamond-surfactant colloids, measure their stability by dynamic light scattering and use quartz crystal microbalance-dissipation, a technique sensitive to surface mass, in order to compare their ability to remove surface-bound model triglyceride lipid with ionic and nonionic aqueous surfactants at 15-25 °C. Oxidized, reduced, ω-alkylcarboxylic acid, and ω-alkylamidoamine surface-modified adducts are prepared, and then characterized by techniques including (13)C cross-polarization (CP) magic-angle spinning (MAS) NMR. Clear improvement in removal of triglyceride was observed in the presence of nanodiamond, even at 15 °C, both with nanodiamond-surfactant colloids, and by prior nanoparticle deposition on interfacial lipid, showing that nanodiamonds are playing a crucial role in the enhancement of the detergency process, providing unique leads in the development of new approaches to low-temperature cleaning.
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Affiliation(s)
- Xianjin Cui
- School of Engineering and Applied Science, Aston University , Birmingham, B4 7ET United Kingdom
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Cuyvers S, Hendrix J, Dornez E, Engelborghs Y, Delcour JA, Courtin CM. Both Substrate Hydrolysis and Secondary Substrate Binding Determine Xylanase Mobility as Assessed by FRAP. J Phys Chem B 2011; 115:4810-7. [DOI: 10.1021/jp110963f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sven Cuyvers
- Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 20 - box 2463, B-3001 Leuven, Belgium
| | - Jelle Hendrix
- Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G - box 2403, B-3001 Leuven, Belgium
| | - Emmie Dornez
- Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 20 - box 2463, B-3001 Leuven, Belgium
| | - Yves Engelborghs
- Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G - box 2403, B-3001 Leuven, Belgium
| | - Jan A. Delcour
- Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 20 - box 2463, B-3001 Leuven, Belgium
| | - Christophe M. Courtin
- Laboratory of Food Chemistry and Biochemistry & Leuven Food Science and Nutrition Research Centre (LFoRCe), Katholieke Universiteit Leuven, Kasteelpark Arenberg 20 - box 2463, B-3001 Leuven, Belgium
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Feller BE, Kellis JT, Cascão-Pereira LG, Robertson CR, Frank CW. Interfacial biocatalysis on charged and immobilized substrates: the roles of enzyme and substrate surface charge. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:250-263. [PMID: 21128607 DOI: 10.1021/la103079t] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An enzyme charge ladder was used to examine the role of electrostatic interactions involved in biocatalysis at the solid-liquid interface. The reactive substrate consisted of an immobilized bovine serum albumin (BSA) multilayer prepared using a layer-by-layer technique. The zeta potential of the BSA substrate and each enzyme variant was measured to determine the absolute charge in solution. Enzyme adsorption and the rate of substrate surface hydrolysis were monitored for the enzyme charge ladder series to provide information regarding the strength of the enzyme-substrate interaction and the rate of interfacial biocatalysis. First, each variant of the charge ladder was examined at pH 8 for various solution ionic strengths. We found that for positively charged variants the adsorption increased with the magnitude of the charge until the surface became saturated. For higher ionic strength solutions, a greater positive enzyme charge was required to induce adsorption. Interestingly, the maximum catalytic rate was not achieved at enzyme saturation but at an invariable intermediate level of adsorption for each ionic strength value. Furthermore, the maximum achievable reaction rate for the charge ladder was larger for higher ionic strength values. We propose that diffusion plays an important role in interfacial biocatalysis, and for strong enzyme-substrate interaction, the rate of diffusion is reduced, leading to a decrease in the overall reaction rate. We investigated the effect of substrate charge by varying the solution pH from 6.1 to 8.7 and by examining multiple ionic strength values for each pH. The same intermediate level of adsorption was found to maximize the overall reaction rate. However, the ionic strength response of the maximum achievable rate was clearly dependent on the pH of the experiment. We propose that this observation is not a direct effect of pH but is caused by the change in substrate surface charge induced by changing the pH. To prove this hypothesis, BSA substrates were chemically modified to reduce the magnitude of the negative charge at pH 8. Chemical modification was accomplished by the amidation of aspartic and glutamic acids to asparagine and glutamine. The ionic strength response of the chemically modified substrate was considerably different than that for the native BSA substrate at an identical pH, consistent with the trend based on substrate surface charge. Consequently, for substrates with a low net surface charge, the maximum achievable catalytic rate of the charge ladder was relatively independent of the solution ionic strength over the range examined; however, at high net substrate surface charge, the maximum rate showed a considerable ionic strength dependence.
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Affiliation(s)
- Bob E Feller
- Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, United States
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Filice M, Romero O, Guisan JM, Palomo JM. trans,trans-2,4-Hexadiene incorporation on enzymes for site-specific immobilization and fluorescent labeling. Org Biomol Chem 2011; 9:5535-40. [DOI: 10.1039/c1ob05401e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Rocha S, Hutchison JA, Peneva K, Herrmann A, Müllen K, Skjøt M, Jørgensen CI, Svendsen A, De Schryver FC, Hofkens J, Uji-i H. Linking Phospholipase Mobility to Activity by Single-Molecule Wide-Field Microscopy. Chemphyschem 2009; 10:151-61. [DOI: 10.1002/cphc.200800537] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Feller BE, Kellis JT, Cascão-Pereira LG, Knoll W, Robertson CR, Frank CW. Fluorescence quantification for surface plasmon excitation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:12303-12311. [PMID: 18844383 DOI: 10.1021/la8013943] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Surface plasmon resonance and surface plasmon fluorescence spectroscopy in combination have the potential to distinguish multicomponent surface processes. However, surface intensity variations from resonance angle shifts lead to a nonlinear response in the fluorescence intensity. We report a method to account for surface intensity variations using the experimentally measured relationship between fluorescence and reflectivity. We apply this method to monitor protease adsorption and proteolytic substrate degradation simultaneously. Multilayer protein substrates are prepared for these degradation studies using a layer-by-layer technique.
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Affiliation(s)
- Bob E Feller
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305-5025, USA
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McClements DJ, Decker EA, Park Y. Controlling Lipid Bioavailability through Physicochemical and Structural Approaches. Crit Rev Food Sci Nutr 2008; 49:48-67. [DOI: 10.1080/10408390701764245] [Citation(s) in RCA: 282] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Mazza D, Braeckmans K, Cella F, Testa I, Vercauteren D, Demeester J, De Smedt SS, Diaspro A. A new FRAP/FRAPa method for three-dimensional diffusion measurements based on multiphoton excitation microscopy. Biophys J 2008; 95:3457-69. [PMID: 18621824 PMCID: PMC2547427 DOI: 10.1529/biophysj.108.133637] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Accepted: 06/23/2008] [Indexed: 11/22/2022] Open
Abstract
We present a new convenient method for quantitative three-dimensionally resolved diffusion measurements based on the photobleaching (FRAP) or photoactivation (FRAPa) of a disk-shaped area by the scanning laser beam of a multiphoton microscope. Contrary to previously reported spot-photobleaching protocols, this method has the advantage of full scalability of the size of the photobleached area and thus the range of diffusion coefficients, which can be measured conveniently. The method is compatible with low as well as high numerical aperture objective lenses, allowing us to perform quantitative diffusion measurements in three-dimensional extended samples as well as in very small volumes, such as cell nuclei. Furthermore, by photobleaching/photoactivating a large area, diffusion along the optical axis can be measured separately, which is convenient when studying anisotropic diffusion. First, we show the rigorous mathematical derivation of the model, leading to a closed-form formula describing the fluorescence recovery/redistribution phase. Next, the ability of the multiphoton FRAP method to correctly measure absolute diffusion coefficients is tested thoroughly on many test solutions of FITC-dextrans covering a wide range of diffusion coefficients. The same is done for the FRAPa method on a series of photoactivatable green fluorescent protein solutions with different viscosities. Finally, we apply the method to photoactivatable green fluorescent protein diffusing freely in the nucleus of living NIH-3T3 mouse embryo fibroblasts.
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Affiliation(s)
- Davide Mazza
- Laboratory for Advanced Microscopy, Bioimaging, and Spectroscopy-MicroSCoBiO Research Center, Department of Physics, University of Genoa, Genoa, Italy.
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Designing Food Structure to Control Stability, Digestion, Release and Absorption of Lipophilic Food Components. FOOD BIOPHYS 2008. [DOI: 10.1007/s11483-008-9070-y] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Sonesson AW, Callisen TH, Brismar H, Elofsson UM. Adsorption and activity of Thermomyces lanuginosus lipase on hydrophobic and hydrophilic surfaces measured with dual polarization interferometry (DPI) and confocal microscopy. Colloids Surf B Biointerfaces 2008; 61:208-15. [PMID: 17890066 DOI: 10.1016/j.colsurfb.2007.08.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 08/14/2007] [Accepted: 08/14/2007] [Indexed: 11/24/2022]
Abstract
The adsorption and activity of Thermomyces lanuginosus lipase (TLL) was measured with dual polarization interferometry (DPI) and confocal microscopy at a hydrophilic and hydrophobic surface. In the adsorption isotherms, it was evident that TLL both had higher affinity for the hydrophobic surface and adsorbed to a higher adsorbed amount (1.90 mg/m(2)) compared to the hydrophilic surface (1.40-1.50mg/m(2)). The thickness of the adsorbed layer was constant (approximately 3.5 nm) on both surfaces at an adsorbed amount >1.0mg/m(2), but decreased on the hydrophilic surface at lower surface coverage, which might be explained by partially unfolding of the TLL structure. However, a linear dependence of the refractive index of the adsorbed layer on adsorbed amount of TLL on C18 surfaces indicated that the structure of TLL was similar at low and high surface coverage. The activity of adsorbed TLL was measured towards carboxyfluorescein diacetate (CFDA) in solution, which upon lipase activity formed a fluorescent product. The surface fluorescence intensity increase was measured in a confocal microscope as a function of time after lipase adsorption. It was evident that TLL was more active on the hydrophilic surface, which suggested that a larger fraction of adsorbed TLL molecules were oriented with the active site facing the solution compared to the hydrophobic surface. Moreover, most of the activity remained when the TLL surface coverage decreased. Earlier reports on TLL surface mobility on the same surfaces have found that the lateral diffusion was highest on hydrophilic surfaces and at low surface coverage of TLL. Hence, a high lateral mobility might lead to a longer exposure time of the active site towards solution, thereby increasing the activity against a water-soluble substrate.
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