Secondary water pore formation for proton transport in a ClC exchanger revealed by an atomistic molecular dynamics simulation

Several prokaryotic ClC proteins have been demonstrated to function as exchangers that transport both chloride ions and protons simultaneously in opposite directions. However, the path of the proton through the ClC exchanger and how the protein brings about the coupled movement of both ions are still unknown. In the present work, we demonstrate that a previously unknown secondary water pore is formed inside a ClC exchanger by using an atomistic molecular dynamics (MD) simulation. From the systematic simulations, it was determined that the glutamate residue exposed to the intracellular solution, E203, plays an important role as a trigger for the formation of the secondary water pore. Based on our simulation results, we conclude that protons in the ClC exchanger are conducted via a water network through the secondary water pore and we propose a new mechanism for the coupled transport of chloride ions and protons

Dispersion of Carbon Nanomaterials and Its Application to Nanocomposites and Transparent Electrodes

OAIID:oai:osos.snu.ac.kr:snu2013-01/104/0000001236/3SEQ:3PERF_CD:SNU2013-01EVAL_ITEM_CD:104USER_ID:0000001236ADJUST_YN:NEMP_ID:A004558DEPT_CD:445CITE_RATE:0FILENAME:초청강연_0312_polychar21.docDEPT_NM:재료공학부EMAIL:[email protected]:

A New Fabrication Method of Polymer Solar Cells

Various approaches for morphology control such as thermal annealing, solvent annealing, and use of additives, have been proposed to enhance the efficiency of polymer solar cells (PSCs). These methods have been very effective to afford nano-scaled phase-separated morphology in lateral direction (parallel to film surface). However, they have a limitation to control the vertical concentration distribution of the components in active layer, although the vertical distribution is very critical for effective transport of charge carriers.OAIID:oai:osos.snu.ac.kr:snu2012-01/104/0000001236/1SEQ:1PERF_CD:SNU2012-01EVAL_ITEM_CD:104USER_ID:0000001236ADJUST_YN:NEMP_ID:A004558DEPT_CD:445CITE_RATE:0FILENAME:2. A New Fabrication Method of Polymer Solar Cells.pdfDEPT_NM:재료공학부EMAIL:[email protected]:

Simple Structured DPP-based Small Molecules for High Efficient Organic Photovoltaics

OAIID:oai:osos.snu.ac.kr:snu2013-01/104/0000001236/8SEQ:8PERF_CD:SNU2013-01EVAL_ITEM_CD:104USER_ID:0000001236ADJUST_YN:NEMP_ID:A004558DEPT_CD:445CITE_RATE:0FILENAME:이종원.pdfDEPT_NM:재료공학부EMAIL:[email protected]:

Synthesis of π-extended low bandgap polymer based on isoindigo and thienyl-vinylene for high-performance polymer solar cells

246th ACS National Meeting and Exposition September 8-12, 2013, Indianapolis, IndianaIn this presentation, we report a novel π-extended low bandgap polymer, PITVT, which is composed of isoindigo and thienylvinylene. The polymer exhibits a high power conversion efficiency of 7.09% for polymer solar cells (PSCs). The high performance is achieved by strong intermolecular π-π stacking from coplanarity of thienylvinylene in polmyer backbone, and the deep HOMO energy level of PITVT. This work clearly demonstrates that the incorporation of π-extended thienylvinylene moiety in conjugated polymer backbone improves the performance of PSCs.OAIID:oai:osos.snu.ac.kr:snu2013-01/104/0000001236/17SEQ:17PERF_CD:SNU2013-01EVAL_ITEM_CD:104USER_ID:0000001236ADJUST_YN:NEMP_ID:A004558DEPT_CD:445CITE_RATE:0FILENAME:정의혁 포스터 초록.pdfDEPT_NM:재료공학부EMAIL:[email protected]:

Isoindigo as a Building Block for Semiconducting Conjugated Polymers for High Performance Organic Photovoltaics

One of the most important issues for enhancing the power conversion efficiency (PCE) of polymer solar cells (PSCs) is the development of conjugated polymers which exhibit broad light absorption with strong absorptivity, high charge carrier mobility, suitable energy level matching with the electron acceptor (fullerene derivatives), and appropriate molecular orientation to form an optimum pathway of charge carriers to the corresponding electrodes. In past few years, remarkable progress in the PCE surpassing 8% have been achieved with the configuration of bulk-heterojunction network structure consisting of high performance conjugated polymer as an electron donor and fullerene derivative as an acceptor. Isoindigo is a dye molecule with two lactam rings pertaining strong electron-withdrawing characteristic and planar ∏-conjugated structure. Particularly, the planar molecular structure is expected to afford high charge carrier mobility. Moreover, isoindigo-based organic compounds show broad optical absorption, high extinction coefficient, and deep HOMO energy level. Therefore, isoindigo is a promising building block for constructing low bandgap conjugated polymers to achieve high performance PSCs.OAIID:oai:osos.snu.ac.kr:snu2014-01/104/0000001236/4SEQ:4PERF_CD:SNU2014-01EVAL_ITEM_CD:104USER_ID:0000001236ADJUST_YN:NEMP_ID:A004558DEPT_CD:445CITE_RATE:0FILENAME:초록및프로그램_5월프랑스.pdfDEPT_NM:재료공학부CONFIRM:

Whole cell biosynthesis of a functional oligosaccharide, 2′-fucosyllactose, using engineered Escherichia coli

BACKGROUND: 2'-Fucosyllactose (2-FL) is a functional oligosaccharide present in human milk which protects against the infection of enteric pathogens. Because 2-FL can be synthesized through the enzymatic fucosylation of lactose with guanosine 5′-diphosphate (GDP)-l-fucose by α-1,2-fucosyltransferase (FucT2), an 2-FL producing Escherichia coli can be constructed through overexpressing genes coding for endogenous GDP- l-fucose biosynthetic enzymes and heterologous fucosyltransferase. RESULTS: The gene for FucT2 from Helicobacter pylori was introduced to the GDP- l-fucose producing recombinant E. coli BL21 star(DE3) strain. However, only small amount of 2-FL was produced in a batch fermentation because the E. coli BL21star(DE3) strain assimilated lactose instead of converting to 2-FL. As an alternative host, the E. coli JM109(DE3) strain which is incapable of assimilating lactose was chosen as a 2-FL producer. Whole cell biosynthesis of 2-FL from lactose was investigated in a series of batch fermentations using various concentrations of lactose. The results of batch fermentations showed that lactose was slowly assimilated by the engineered E. coli JM109(DE3) strain and 2-FL was synthesized without supplementation of another auxiliary sugar for cell growth. A maximum 2-FL concentration of 1.23 g/l was obtained from a batch fermentation with 14.5 g/l lactose. The experimentally obtained yield (g 2-FL/g lactose) corresponded to 20% of the theoretical maximum yield estimated by the elementary flux mode (EFM) analysis. CONCLUSIONS: The experimental 2-FL yield in this study corresponded to about 20% of the theoretical maximum yield, which suggests further modifications via metabolic engineering of a host strain or optimization of fermentation processes might be carried out for improving 2-FL yield. Improvement of microbial production of 2-FL from lactose by engineered E. coli would increase the feasibility of utilizing 2-FL as a prebiotic in various foods