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Your search keyword '"Li, Je-Luen"' showing total 28 results
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28 results on '"Li, Je-Luen"'

3. Single-image diffusion coefficient measurements of proteins in free solution

Author

Zareh, Shannon Kian, DeSantis, Michael C., Kessler, Jonathan, Li, Je-Luen, and Wang, Y. M.

Subjects
Quantitative Biology - Biomolecules, Condensed Matter - Soft Condensed Matter, Physics - Biological Physics, Quantitative Biology - Quantitative Methods
Abstract

Diffusion coefficient measurements are important for many biological and material investigations, such as particle dynamics, kinetics, and size determinations. Amongst current measurement methods, single particle tracking (SPT) offers the unique capability of providing location and diffusion information of a molecule simultaneously while using only femptomoles of sample. However, the temporal resolution of SPT is limited to seconds for single-color labeled samples. By directly imaging three dimensional (3D) diffusing fluorescent proteins and studying the widths of their intensity profiles, we determine the proteins' diffusion coefficients using single protein images of sub-millisecond exposure times. This simple method improves the temporal resolution of diffusion coefficient measurements to sub-millisecond, and can be readily applied to a range of particle sizes in SPT investigations and applications where diffusion coefficient measurements are needed, such as reaction kinetics and particle size determinations.

Published
2011

4. Protein sliding and hopping kinetics on DNA

Author

DeSantis, Michael C., Li, Je-Luen, and Wang, Y. M.

Subjects
Physics - Biological Physics, Quantitative Biology - Biomolecules
Abstract

Using Monte-Carlo simulations, we deconvolved the sliding and hopping kinetics of GFP-LacI proteins on elongated DNA from their experimentally observed seconds-long diffusion trajectories. Our simulations suggest the following results: (1) in each diffusion trajectory, a protein makes on average hundreds of alternating slides and hops with a mean sliding time of several tens of ms; (2) sliding dominates the root mean square displacement of fast diffusion trajectories, whereas hopping dominates slow ones; (3) flow and variations in salt concentration have limited effects on hopping kinetics, while in vivo DNA configuration is not expected to influence sliding kinetics; furthermore, (4) the rate of occurrence for hops longer than 200 nm agrees with experimental data for EcoRV proteins.

Published
2010
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5. Precision analysis for standard deviation measurements of single fluorescent molecule images

Author

DeSantis, Michael C., DeCenzo, Shawn H., Li, Je-Luen, and Wang, Y. M.

Subjects
Quantitative Biology - Quantitative Methods, Quantitative Biology - Biomolecules
Abstract

Standard deviation measurements of intensity profiles of stationary single fluorescent molecules are useful for studying axial localization, molecular orientation, and a fluorescence imaging system's spatial resolution. Here we report on the analysis of the precision of standard deviation measurements of intensity profiles of single fluorescent molecules imaged using an EMCCD camera. We have developed an analytical expression for the standard deviation measurement error of a single image which is a function of the total number of detected photons, the background photon noise, and the camera pixel size. The theoretical results agree well with the experimental, simulation, and numerical integration results. Using this expression, we show that single-molecule standard deviation measurements offer nanometer precision for a large range of experimental parameters., Comment: 16 pages, 3 figures, revised

Published
2009
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8. Structural Basis of AZD9291 Selectivity for EGFR T790M

Author

Yan, Xiao-E, primary, Ayaz, Pelin, additional, Zhu, Su-Jie, additional, Zhao, Peng, additional, Liang, Ling, additional, Zhang, Casey H., additional, Wu, Ya-Chuang, additional, Li, Je-Luen, additional, Choi, Hwan Geun, additional, Huang, Xin, additional, Shan, Yibing, additional, Shaw, David E., additional, and Yun, Cai-Hong, additional

Published
2020
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28. Effects of linker length on phase separation: lessons from the Rubisco-EPYC1 system of the algal pyrenoid.

Author

GrandPre T, Zhang Y, Pyo AGT, Weiner B, Li JL, Jonikas MC, and Wingreen NS

Abstract

Biomolecular condensates are membraneless organelles formed via phase separation of macromolecules, typically consisting of bond-forming "stickers" connected by flexible "linkers". Linkers have diverse roles, such as occupying space and facilitating interactions. To understand how linker length relative to other lengths affects condensation, we focus on the pyrenoid, which enhances photosynthesis in green algae. Specifically, we apply coarse-grained simulations and analytical theory to the pyrenoid proteins of Chlamydomonas reinhardtii : the rigid holoenzyme Rubisco and its flexible partner EPYC1. Remarkably, halving EPYC1 linker lengths decreases critical concentrations by ten-fold. We attribute this difference to the molecular "fit" between EPYC1 and Rubisco. Varying Rubisco sticker locations reveals that the native sites yield the poorest fit, thus optimizing phase separation. Surprisingly, shorter linkers mediate a transition to a gas of rods as Rubisco stickers approach the poles. These findings illustrate how intrinsically disordered proteins affect phase separation through the interplay of molecular length scales., Competing Interests: Competing interests The authors declare no competing interests.

Published
2023
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