• BMB Reports
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• 제34권5호
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• pp.446-451
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• 2001

The interaction of cytochrome c with binary phospholipid mixtures was investigated by solid-state $^2H$- and $^{31}P$-NMR. To examine the effect of the interaction on the glycerol backbones, the glycerol moieties of phosphatidylcholine (PC), and cardioliph (CL) were specifically deuterated. On the binding of cytochrome c to the binary mixed bilayers, no changes in the quadrupole splittings of each of the components were observed for the PC/PG, PE/CL and PE/PG liposomes. In contrast, the splittings of CL decreased on binging of protein to the PC/CL liposomes, although those of PC did not change at all. This showed that cytochrome c specifically interacts with CL in PC/CL bilayers, and penetrates into the lipid bilayer to some extent so as to perturb the dynamic structure of the glycerol backbone. This is distinctly different from the mode of interaction of cytochrome c with other binary mixed bilayers. In the $^{31}P$-NMR spectra, line broadening and a decrease of the chemical shift anisotropy were observed on the binding of cytochrome c for all binary mixed bilayers that were examined. These changes were more significant for the PC/CL bilayers. Furthermore, the line broadening is more significant for PC than for CL in PC/CL bilayers. Therefore, it can be concluded that with the polar head groups, not only CL but also PC are involved in the interaction with cytochrome c.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.880-888
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• 2006

Pleurocidin, an $\alpha$-helical cationic antimicrobial peptide, was isolated from skin mucosa of winter flounder (Pleuronectes americamus). It had strong antimicrobial activities against Gram-positive and Gram-negative bacteria, but had very weak hemolytic activity. The Gly$^{13,17}\rightarrow$Ala analog (pleurocidin-AA) showed similar antibacterial activities, but had dramatically increased hemolytic activity. The bacterial cell selectivity of pleurocidin was confirmed through the membrane-disrupting and membrane-binding affinities using dye leakage, tryptophan fluorescence blue shift, and tryptophan quenching experiments. However, the non-cell-selective antimicrobial peptide, pleurocidin-AA, interacts strongly with both negatively charged and zwitterionic phospholipid membranes, the latter of which are the major constituents of the outer leaflet of erythrocytes. Circular dihroism spectra showed that pleurocidin-AA has much higher contents of $\alpha$-helical conformation than pleurocidin. The tertiary structure determined by NMR spectroscopy showed that pleurocidin has a flexible. structure between the long helix from $Gly^3$ to $Gly^{17}$ and the short helix from $Gly^{17}$ to $Leu^{25}$. Cell-selective antimicrobial peptide pleurocidin interacts strongly with negatively charged phospholipid membranes, which mimic bacterial membranes. Structural flexibility between the two helices may play a key role in bacterial cell selectivity of pleurocidin.

• 공업화학
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• 제29권2호
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• pp.244-247
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• 2018

쌍성이온 인지질의 한 종류인 lecithin은 decane과 같은 유기용매상에서 구 모양의 역마이셀을 만든다. 이러한 lecithin을 포함하고 있는 유기졸에 염화칼슘과 같은 다원자가의 이온을 첨가하면 유기젤이 형성된다. 이러한 유기젤은 연료의 젤화, 음식 준비, 약물전달 등에 다양하게 활용될 수 있다. 본 연구에서는 이러한 젤의 온도 영향을 유변학적 관점에서 조사하였다. 유기젤의 유변학 연구를 통하여 유기젤의 녹는점(${\sim}95^{\circ}C$)과 온도가 증가하면서 젤의 고체와 같은 성질이 줄어듦을 확인하였다. 온도가 증가함에 따라서 유기젤의 고체와 같은 성질이 줄어드는 이유는 lecithin과 염화칼슘 사이의 정전기적 상호작용이 약해지기 때문으로 판단된다.

• 공업화학
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• 제32권6호
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• pp.679-683
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• 2021

양친매성 인지질의 한 종류인 레시틴은 데케인과 같은 비극성 유기용매상에서 구형의 역마이셀을 형성한다. 염화리튬과 같은 이온이 레시틴용액에 첨가될 때, 유기졸이 역실린더형 마이셀의 얽힘으로 인해 유기젤로 변환하게 된다. 이번 연구에서, 우리는 레시틴과 염화리튬 혼합물의 유변학적 성질에 대한 보조계면활성제로서의 펜탄올 효과를 연구하고자 한다. 유변학 연구를 통해, 유기젤에 펜탄올이 첨가될 때, 유기젤의 점도와 탄성 성질이 감소하였다. 이러한 감소는 역실린더 마이셀의 길이의 감소가 그 원인이며, 엑스선 소각 산란분석기를 통해 이를 확인하였다.