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Adsorption free energy predicts amyloid protein nucleation rates. Proc Natl Acad Sci U S A 2022; 119:e2109718119. [PMID: 35901206 PMCID: PMC9351353 DOI: 10.1073/pnas.2109718119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Primary nucleation is the fundamental event that initiates the conversion of proteins from their normal physiological forms into pathological amyloid aggregates associated with the onset and development of disorders including systemic amyloidosis, as well as the neurodegenerative conditions Alzheimer's and Parkinson's diseases. It has become apparent that the presence of surfaces can dramatically modulate nucleation. However, the underlying physicochemical parameters governing this process have been challenging to elucidate, with interfaces in some cases having been found to accelerate aggregation, while in others they can inhibit the kinetics of this process. Here we show through kinetic analysis that for three different fibril-forming proteins, interfaces affect the aggregation reaction mainly through modulating the primary nucleation step. Moreover, we show through direct measurements of the Gibbs free energy of adsorption, combined with theory and coarse-grained computer simulations, that overall nucleation rates are suppressed at high and at low surface interaction strengths but significantly enhanced at intermediate strengths, and we verify these regimes experimentally. Taken together, these results provide a quantitative description of the fundamental process which triggers amyloid formation and shed light on the key factors that control this process.
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Cristofolini L, Orsi D, Isa L. Characterization of the dynamics of interfaces and of interface-dominated systems via spectroscopy and microscopy techniques. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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McUmber AC, Larson NR, Randolph TW, Schwartz DK. Molecular trajectories provide signatures of protein clustering and crowding at the oil/water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:5882-5890. [PMID: 25950404 DOI: 10.1021/acs.langmuir.5b00984] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using high throughput single-molecule total internal reflection fluorescence microscopy (TIRFM), we have acquired molecular trajectories of bovine serum albumin (BSA) and hen egg white lysozyme during protein layer formation at the silicone oil-water interface. These trajectories were analyzed to determine the distribution of molecular diffusion coefficients, and for signatures of molecular crowding/caging, including subdiffusive motion and temporal anticorrelation of the instantaneous velocity vector. The evolution of these properties with aging time of the interface was compared with dynamic interfacial tension measurements. For both lysozyme and BSA, we observed an overall slowing of protein objects, the onset of both subdiffusive and anticorrelated motion (associated with crowding), and a decrease in the interfacial tension with aging time. For lysozyme, all of these phenomena occurred virtually simultaneously, consistent with a homogeneous model of layer formation that involves gradual crowding of weakly interacting proteins. For BSA, however, the slowing occurred first, followed by the signatures of crowding/caging, followed by a decrease in interfacial tension, consistent with a heterogeneous model of layer formation involving the formation of protein clusters. The application of microrheological methods to single molecule trajectories described here provides an unprecedented level of mechanistic interpretation of interfacial events that occurred over a wide range of interfacial protein coverage.
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Affiliation(s)
- Aaron C McUmber
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Nicholas R Larson
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Theodore W Randolph
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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Affiliation(s)
- Shanghao Li
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Cox Science Center, Coral
Gables, Florida 33146, United States
| | - Roger M. Leblanc
- Department of Chemistry, University of Miami, 1301 Memorial Drive, Cox Science Center, Coral
Gables, Florida 33146, United States
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Li P, Nielsen HM, Fano M, Müllertz A. Preparation and characterization of insulin-surfactant complexes for loading into lipid-based drug delivery systems. J Pharm Sci 2013; 102:2689-98. [PMID: 23839923 DOI: 10.1002/jps.23640] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 04/26/2013] [Accepted: 05/07/2013] [Indexed: 11/09/2022]
Abstract
Insulin suffers from poor oral bioavailability, but lipid-based drug delivery systems (DDS) may constitute promising tools for improving this. Loading of protein drugs into lipid matrices may, however, be challenging, and different formulation approaches must be taken to achieve sufficient loading and preservation of native structure. The aim of the present study was to characterize insulin after complexation with biocompatible surfactants to improve loading into lipid-based DDS. Insulin-surfactant complexes were prepared by freeze-drying with distearyldimethylammonium bromide or soybean phospholipid as complexing surfactant and dimethyl sulfoxide (DMSO) as solvent. Significant change in secondary structure of insulin freeze dried from DMSO was observed using Fourier transform infrared spectroscopy. Changes were quantitatively smaller in the presence of surfactants, demonstrating both a stabilizing effect of surfactants, but also a nonnative secondary structure in the solid state. Finally, circular dichroism analysis of rehydrated complexes showed that the processing did not irreversibly alter the secondary structure of insulin. In short, the present study demonstrates changes in the secondary structure of insulin after freeze-drying from DMSO, constituting a potential generic issue with this technique for protein processing. In the specific case of insulin, the changes were found to be reversible, explaining the success of this strategy in previous studies.
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Affiliation(s)
- Ping Li
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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Koynov K, Butt HJ. Fluorescence correlation spectroscopy in colloid and interface science. Curr Opin Colloid Interface Sci 2012. [DOI: 10.1016/j.cocis.2012.09.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Jorgensen L, Bennedsen P, Hoffmann SV, Krogh RL, Pinholt C, Groenning M, Hostrup S, Bukrinsky JT. Adsorption of insulin with varying self-association profiles to a solid Teflon surface—Influence on protein structure, fibrillation tendency and thermal stability. Eur J Pharm Sci 2011; 42:509-16. [DOI: 10.1016/j.ejps.2011.02.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 12/17/2010] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
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Martin-Gassin G, Gassin PM, Couston L, Diat O, Benichou E, Brevet PF. Second harmonic generation monitoring of nitric acid extraction by a monoamide at the water–dodecane interface. Phys Chem Chem Phys 2011; 13:19580-6. [DOI: 10.1039/c1cp22179e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Macháň R, Hof M. Recent developments in fluorescence correlation spectroscopy for diffusion measurements in planar lipid membranes. Int J Mol Sci 2010; 11:427-457. [PMID: 20386647 PMCID: PMC2852847 DOI: 10.3390/ijms11020427] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 01/11/2010] [Accepted: 01/15/2010] [Indexed: 12/11/2022] Open
Abstract
Fluorescence correlation spectroscopy (FCS) is a single molecule technique used mainly for determination of mobility and local concentration of molecules. This review describes the specific problems of FCS in planar systems and reviews the state of the art experimental approaches such as 2-focus, Z-scan or scanning FCS, which overcome most of the artefacts and limitations of standard FCS. We focus on diffusion measurements of lipids and proteins in planar lipid membranes and review the contributions of FCS to elucidating membrane dynamics and the factors influencing it, such as membrane composition, ionic strength, presence of membrane proteins or frictional coupling with solid support.
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Affiliation(s)
- Radek Macháň
- J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i., Dolejškova 2155/3, 182 23 Prague, Czech Republic; E-Mail:
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of ASCR, v.v.i., Dolejškova 2155/3, 182 23 Prague, Czech Republic; E-Mail:
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Sivozhelezov V, Bruzzese D, Pastorino L, Pechkova E, Nicolini C. Increase of catalytic activity of lipase towards olive oil by Langmuir-film immobilization of lipase. Enzyme Microb Technol 2009. [DOI: 10.1016/j.enzmictec.2008.10.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Donsmark J, Rischel C. Fluorescence correlation spectroscopy at the oil-water interface: hard disk diffusion behavior in dilute beta-lactoglobulin layers precedes monolayer formation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:6614-23. [PMID: 17497902 DOI: 10.1021/la063547l] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We have performed a thorough characterization of fluorescence correlations spectroscopy (FCS) applied to oil-water interfaces of viscous oil droplets in aqueous solution, including numerical wave-optical calculations of the detection geometry and regularized multicomponent analysis of sample data. It is shown how significant errors in the estimation of the surface concentration can be avoided when FCS is applied to an interface region. We present data on the adsorption dynamics of beta-lactoglobulin (BLG), a well-studied model system. It is found that electrostatic repulsion slows the adsorption process and reduces the initial saturation density far below the monolayer concentration. During the first stages of adsorption, the diffusion coefficients of adsorbed protein closely follow the 2D hard disk model of Lahtinen et al.1 in response to increased surface concentration, which suggests that protein-protein interactions are limited to long-range Coulombic interactions at this stage.
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Affiliation(s)
- Jesper Donsmark
- Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen, Denmark.
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Taluja A, Bae YH. Role of a novel excipient poly(ethylene glycol)-b-poly(L-histidine) in retention of physical stability of insulin at aqueous/organic interface. Mol Pharm 2007; 4:561-70. [PMID: 17439239 PMCID: PMC2562025 DOI: 10.1021/mp060120z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim of this study was to investigate whether a cationic polyelectrolyte, poly(ethylene glycol)-b-poly(L-histidine) diblock copolymer (PEG-polyHis), can stabilize insulin, at the aqueous/methylene chloride interface formed during the microencapsulation process. Insulin aggregation at this interface was monitored spectrophotometrically at 276 nm. The effects of protein concentration, pH of the aqueous medium, and the presence of poly(lactic-co-glycolic acid) (PLGA) in methylene chloride (MC) on insulin aggregation were observed. For the 2.0 mg/mL insulin solutions in phosphate buffer (PB), the effect of addition of Pluronic F-127 as a positive control and addition of PEG-polyHis as a novel excipient in PB was also evaluated at various insulin/polymeric excipient weight ratios. The conformation of insulin protected by PEG-polyHis and recovered after interfacial exposure was evaluated via circular dichroism (CD) spectroscopy. Greater loss in soluble insulin was observed with increasing insulin concentrations. pH 6.0 was selected for optimal ionic interactions between insulin and PEG-polyHis based on zeta potential and particle size studies. pH 4.5 and 7.4 (no ionic complexation between insulin and PEG-polyHis) were selected as controls to compare the stabilization effect of PEG-polyHis with that at pH 6.0. Incubation of PEG-polyHis with insulin at pH 6.0 drastically reduced protein aggregation, even in the presence of PLGA. PEG-polyHis and F-127 reduced insulin aggregation in noncomplexing pH conditions pointing to the role played by PEG in modulation of insulin adsorption at the interface. Far-UV (205-250 nm) CD study revealed negligible qualitative effects on soluble insulin's secondary structure after interfacial exposure. RP-HPLC and size-exclusion HPLC showed no deamidation of insulin or formation of soluble high molecular weight transformation products respectively. MALDI-TOF mass spectrometry confirmed the results from chromatographic procedures. Radioimmunoassay carried out on select samples showed that recovered soluble insulin had retained its immunoreactivity. An experimental method to simulate interfacial denaturation of proteins was designed for assessment of protein stability at the interface and screening for novel protein stabilizers. Understanding and manipulation of such polyelectrolyte-insulin complexation will likely play a role in insulin controlled delivery via microsphere formulation(s).
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Affiliation(s)
- Ajay Taluja
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah 84108, USA
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