Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Fang-Yu Chen is active.

Publication


Featured researches published by Fang-Yu Chen.


Biophysical Journal | 2003

Evidence for Membrane Thinning Effect as the Mechanism for Peptide-Induced Pore Formation

Fang-Yu Chen; Ming-Tao Lee; Huey W. Huang

Antimicrobial peptides have two binding states in a lipid bilayer, a surface state S and a pore-forming state I. The transition from the S state to the I state has a sigmoidal peptide-concentration dependence indicating cooperativity in the peptide-membrane interactions. In a previous paper, we reported the transition of alamethicin measured in three bilayer conditions. The data were explained by a free energy that took into account the membrane thinning effect induced by the peptides. In this paper, the full implications of the free energy were tested by including another type of peptide, melittin, that forms toroidal pores, instead of barrel-stave pores as in the case of alamethicin. The S-to-I transitions were measured by oriented circular dichroism. The membrane thinning effect was measured by x-ray diffraction. All data were in good agreement with the theory, indicating that the membrane thinning effect is a plausible mechanism for the peptide-induced pore formations.


Biophysical Journal | 2002

Sigmoidal concentration dependence of antimicrobial peptide activities: A case study on alamethicin

Fang-Yu Chen; Ming-Tao Lee; Huey W. Huang

The transition of the state of alamethicin from its inactive state to its active state of pore formation was measured as a function of the peptide concentration in three different membrane conditions. In each case the fraction of the alamethicin molecules occupying the active state, phi, showed a sigmoidal concentration dependence that is typical of the activities of antimicrobial peptides. Such a concentration dependence is often interpreted as due to peptide aggregation. However, we will show that a simple effect of aggregation cannot explain the data. We will introduce a model based on the elasticity of membrane, taking into consideration the membrane-thinning effect due to protein inclusion. The elastic energy of membrane provides an additional driving force for aggregation. The model produces a relation that not only predicts the correct concentration dependence but also explains qualitatively how the dependence changes with membrane conditions. The result shows that the membrane-mediated interactions between monomers and aggregates are essential for the strong cooperativity shown in pore formation.


Biophysical Journal | 2008

Membrane-Thinning Effect of Curcumin

Wei-Chin Hung; Fang-Yu Chen; Chang-Chun Lee; Yen Sun; Ming-Tao Lee; Huey W. Huang

Interaction of curcumin with lipid bilayers is not well understood. A recent experiment showed that curcumin significantly affected the single-channel lifetime of gramicidin in a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer without affecting its single-channel conductance. We performed two experiments to understand this result. By isothermal titration calorimetry, we measured the partition coefficient of curcumin binding to DOPC bilayers. By x-ray lamellar diffraction, we measured the thickness change of DOPC bilayers as a function of the curcumin/lipid ratio. A nonlinear membrane-thinning effect by curcumin was discovered. The gramicidin data were qualitatively interpreted by the combination of isothermal titration calorimetry and x-ray results. We show that not only does curcumin thin the lipid bilayer, it might also weaken its elasticity moduli. The result implies that curcumin may affect the function of membrane proteins by modifying the properties of the host membrane.


Biophysical Journal | 2009

Interaction of Tea Catechin (—)-Epigallocatechin Gallate with Lipid Bilayers

Yen Sun; Wei-Chin Hung; Fang-Yu Chen; Chang-Chun Lee; Huey W. Huang

A major component of green tea extracts, catechin (-)-Epigallocatechin gallate (EGCg), has been reported to be biologically active and interacting with membranes. A recent study reported drastic effects of EGCg on giant unilamellar vesicles (GUVs). In particular, EGCg above 30 microM caused GUVs to burst. Here we investigated the effect of EGCg on single GUVs at lower concentrations, believing that its molecular mechanism would be more clearly revealed. We used the micropipette aspiration method, by which the changes of surface area and volume of a GUV could be measured as a result of interaction with EGCg. We also used x-ray diffraction to measure the membrane thinning effect by EGCg. To understand the property of EGCg, we compared its effect with other membrane-active molecules, including pore-forming peptide magainin, the turmeric (curry) extract curcumin, and detergent Triton X100. We found the effect of EGCg somewhat unique. Although EGCg readily binds to lipid bilayers, its membrane area expansion effect is one order of magnitude smaller than curcumin. EGCg also solubilizes lipid molecules from lipid bilayers without forming pores, but its effect is different from that of Triton X100.


Biophysical Journal | 2008

The Bound States of Amphipathic Drugs in Lipid Bilayers: Study of Curcumin

Yen Sun; Chang-Chun Lee; Wei-Chin Hung; Fang-Yu Chen; Ming-Tao Lee; Huey W. Huang

Drug-membrane interactions are well known but poorly understood. Here we describe dual measurements of membrane thickness change and membrane area change due to the binding of the amphipathic drug curcumin. The combined results allowed us to analyze the binding states of a drug to lipid bilayers, one on the water-membrane interface and another in the hydrocarbon region of the bilayer. The transition between the two states is strongly affected by the elastic energy of membrane thinning (or, equivalently, area stretching) caused by interfacial binding. The data are well described by a two-state model including this elastic energy. The binding of curcumin follows a common pattern of amphipathic peptides binding to membranes, suggesting that the binding states of curcumin are typical for amphipathic drugs.


Physical Review Letters | 2004

Molecular mechanism of Peptide-induced pores in membranes.

Huey W. Huang; Fang-Yu Chen; Ming-Tao Lee


Biochemistry | 2004

Energetics of Pore Formation Induced by Membrane Active Peptides

Ming-Tao Lee; Fang-Yu Chen; Huey W. Huang


Biophysical Journal | 2007

The Condensing Effect of Cholesterol in Lipid Bilayers

Wei-Chin Hung; Ming-Tao Lee; Fang-Yu Chen; Huey W. Huang


Biophysical Journal | 2005

Many-Body Effect of Antimicrobial Peptides: On the Correlation Between Lipid’s Spontaneous Curvature and Pore Formation

Ming-Tao Lee; Wei-Chin Hung; Fang-Yu Chen; Huey W. Huang


Biophysical Journal | 2009

PosterInterfacial Protein-Lipid Interactions IInteraction of Tea Catechin (−)-Epigallocatechin Gallate with Lipid Bilayers

Yen Sun; Wei-Chin Hung; Fang-Yu Chen; Chang-Chun Lee; Huey W. Huang

Collaboration


Dive into the Fang-Yu Chen's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar

Ming-Tao Lee

National Central University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge