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Joniova J, Rebič M, Strejčková A, Huntosova V, Staničová J, Jancura D, Miskovsky P, Bánó G. Formation of Large Hypericin Aggregates in Giant Unilamellar Vesicles-Experiments and Modeling. Biophys J 2017; 112:966-975. [PMID: 28297655 DOI: 10.1016/j.bpj.2017.01.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 12/16/2016] [Accepted: 01/24/2017] [Indexed: 11/25/2022] Open
Abstract
The incorporation of hypericin (Hyp) from aqueous solutions into giant unilamellar vesicle (GUV) membranes has been studied experimentally and by means of kinetic Monte Carlo modeling. The time evolution of Hyp fluorescence originating from Hyp monomers dissolved in the GUV membrane has been recorded by confocal microscopy and while trapping individual GUVs in optical tweezers. It was shown that after reaching a maximum, the fluorescence intensity gradually decreased toward longer times. Formation of oversized Hyp clusters has been observed on the GUV surface at prolonged time. A simplified kinetic Monte Carlo model is presented to follow the aggregation/dissociation processes of Hyp molecules in the membrane. The simulation results reproduced the basic experimental observations: the scaling of the characteristic fluorescence decay time with the vesicle diameter and the buildup of large Hyp clusters in the GUV membrane.
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Affiliation(s)
- Jaroslava Joniova
- Department of Biophysics, Institute of Physics, Faculty of Science, P.J. Šafárik University, Košice, Slovakia; Laboratory of Organometallic and Medicinal Chemistry, ISIC, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Matúš Rebič
- Department of Biophysics, Institute of Physics, Faculty of Science, P.J. Šafárik University, Košice, Slovakia
| | - Alena Strejčková
- Department of Chemistry, Biochemistry and Biophysics, Institute of Biophysics, University of Veterinary Medicine and Pharmacy, Košice, Slovakia
| | - Veronika Huntosova
- Center for Interdisciplinary Biosciences, Faculty of Science, P.J. Šafárik University, Košice, Slovakia
| | - Jana Staničová
- Department of Chemistry, Biochemistry and Biophysics, Institute of Biophysics, University of Veterinary Medicine and Pharmacy, Košice, Slovakia
| | - Daniel Jancura
- Department of Biophysics, Institute of Physics, Faculty of Science, P.J. Šafárik University, Košice, Slovakia; Center for Interdisciplinary Biosciences, Faculty of Science, P.J. Šafárik University, Košice, Slovakia
| | - Pavol Miskovsky
- Department of Biophysics, Institute of Physics, Faculty of Science, P.J. Šafárik University, Košice, Slovakia; Center for Interdisciplinary Biosciences, Faculty of Science, P.J. Šafárik University, Košice, Slovakia
| | - Gregor Bánó
- Department of Biophysics, Institute of Physics, Faculty of Science, P.J. Šafárik University, Košice, Slovakia; Center for Interdisciplinary Biosciences, Faculty of Science, P.J. Šafárik University, Košice, Slovakia.
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Le S, Yao M, Chen J, Efremov AK, Azimi S, Yan J. Disturbance-free rapid solution exchange for magnetic tweezers single-molecule studies. Nucleic Acids Res 2015; 43:e113. [PMID: 26007651 PMCID: PMC4787821 DOI: 10.1093/nar/gkv554] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 05/15/2015] [Indexed: 11/16/2022] Open
Abstract
Single-molecule manipulation technologies have been extensively applied to studies of the structures and interactions of DNA and proteins. An important aspect of such studies is to obtain the dynamics of interactions; however the initial binding is often difficult to obtain due to large mechanical perturbation during solution introduction. Here, we report a simple disturbance-free rapid solution exchange method for magnetic tweezers single-molecule manipulation experiments, which is achieved by tethering the molecules inside microwells (typical dimensions–diameter (D): 40–50 μm, height (H): 100 μm; H:D∼2:1). Our simulations and experiments show that the flow speed can be reduced by several orders of magnitude near the bottom of the microwells from that in the flow chamber, effectively eliminating the flow disturbance to molecules tethered in the microwells. We demonstrate a wide scope of applications of this method by measuring the force dependent DNA structural transitions in response to solution condition change, and polymerization dynamics of RecA on ssDNA/SSB-coated ssDNA/dsDNA of various tether lengths under constant forces, as well as the dynamics of vinculin binding to α-catenin at a constant force (< 5 pN) applied to the α-catenin protein.
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Affiliation(s)
- Shimin Le
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Mingxi Yao
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Jin Chen
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Artem K Efremov
- Mechanobiology Institute, National University of Singapore, 117411, Singapore
| | - Sara Azimi
- Department of Physics, National University of Singapore, 117542, Singapore
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore, 117411, Singapore Department of Physics, National University of Singapore, 117542, Singapore Centre for Bioimaging Sciences, National University of Singapore, 117557, Singapore
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