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Сожалеем, но текст оригинала доступен только зарегистрированным пользователям.	In silico simulation of silver and copper ions interacting with fungal cell wall. mclaudt 19.01.13 в 08:21 0	+1
	In vitro antifungal activity of copper ions and silver ions. mclaudt 19.01.13 в 08:23 0
	Annotation mclaudt 19.01.13 в 08:24 0
	The interaction of silver and copper ions with chitin dimers was modelled using quantum chemistry within the DFT framework. mclaudt 19.01.13 в 08:22 0	+2
	A variation of parameters of hydrogen bonds depending on the presence of different metal atoms was obtained. mclaudt 19.01.13 в 08:40 0	+5
	This variation was compared with the results of in vitro study of antifungal activity of corresponding metal ions. mclaudt 19.01.13 в 08:50 0	+4
	Introduction mclaudt 19.01.13 в 08:51 0
	Silver has long been known to serve as antibacterial and antifungal agent. mclaudt 19.01.13 в 08:54 0	+2
	Out of all the metals with similar antimicrobial properties, silver has the least toxicity to human cells. mclaudt 19.01.13 в 09:00 0	+1
	Prior to the introduction of modern antibiotics, silver was commonly used in medical treatments. mclaudt 19.01.13 в 09:04 0	+2
	- mclaudt 19.01.13 в 10:48 0
	The exact mechanism of antifungal activity is still unknown, and is currently the subject of many research. mclaudt 19.01.13 в 09:11 0	+1
	There is three suggested qualitative concepts: DNA association, cell wall damage and deactivation of enzymes. mclaudt 19.01.13 в 09:32 0
	On the molecular level it is known that silver is capable to form a bond with S, N, and O atoms, and also to catalyze the formation of disulfide bonds. mclaudt 19.01.13 в 09:41 0
	- mclaudt 19.01.13 в 10:48 0
	The new computational quantum chemistry methods make it possible to directly simulate biochemical processes which involve large molecules. mclaudt 19.01.13 в 09:46 0
	In this work the interaction of silver and copper ions with chitin dimers was modelled using the DFT theory. mclaudt 19.01.13 в 09:47 0
	Methods mclaudt 19.01.13 в 09:47 0
	Fungal cell wall simulated as two chitin dimers. mclaudt 19.01.13 в 09:48 0
	To obtain the optimized geometry of ground state, several DFT codes were used, including PC GAMESS, SIESTA and ABINIT. mclaudt 19.01.13 в 09:52 0
	Pic. 1. Conceptual map of DFT method. mclaudt 19.01.13 в 09:52 0
	To find the most probable area of metal adsorption on a molecule, Fukui functions scheme was used. mclaudt 19.01.13 в 09:54 0
	Pic. 2. Visualisation of a scalar electrophilic Fukui function, mapped onto the isosurface of electron density field for detection of probable adsorption site. mclaudt 19.01.13 в 09:58 0
	Electron density of ground state chitin system with adsorbed metal atoms was projected on atomic sites, responsible for hydrogen bond formation, using Hirshfeld method. mclaudt 19.01.13 в 10:00 0
	Calculations were performed on Linux-cluster using parallel MPI (MPICH2) и SMP (OpenMP) parallel paradigms. mclaudt 19.01.13 в 10:06 0
	In silico calculations were complemented by in vitro assay, in which we compared antifungal activity of silver and copper ions in the same concentrations against Alternaria alternata. mclaudt 19.01.13 в 10:09 0
	Results mclaudt 19.01.13 в 10:11 0
	Chitin dimers form the hydrogen bonds with each other, and there is a variability of parameters of that bond depending on type of adsorbed atom near bond. mclaudt 19.01.13 в 10:15 0
	Adsorbed silver atom increases the symmetry of H-bond, measured by the difference of projected charges on oxygen atoms, involved in H-bond, whereas copper atom decreases that symmetry, comparing to the original system without any metal. mclaudt 19.01.13 в 10:20 0
	Pic. 3. Ground state geometry of chitin dimers with silver atoms adsorded. Hydrogen bonds are shown by dash lines. mclaudt 19.01.13 в 10:23 0
	Projected atomic charge is shown near atom. mclaudt 19.01.13 в 10:24 0
	Pic. 4. Difference between the effects of adsorbed copper and silver on hydrogen bonds between chitin dimers. mclaudt 19.01.13 в 10:26 0
	Arrow depicts the polarity of Me-O bond. mclaudt 19.01.13 в 10:26 0
	Tab. 1. Calculated values of hydrogen bond parameters for original system and system witth metal atoms. mclaudt 19.01.13 в 10:27 0
	System mclaudt 19.01.13 в 10:27 0
	Total charge mclaudt 19.01.13 в 10:27 0
	Length mclaudt 19.01.13 в 10:27 0
	H-bond mclaudt 19.01.13 в 10:28 0
	Charge of farthest oxygen atom mclaudt 19.01.13 в 10:28 0
	Charge of nearest oxygen atom mclaudt 19.01.13 в 10:29 0
	Charge of metal atom mclaudt 19.01.13 в 10:29 0
	Charge on hydrogen atom mclaudt 19.01.13 в 10:29 0
	Chitin mclaudt 19.01.13 в 10:29 0
	Chitin + Ag mclaudt 19.01.13 в 10:29 0
	Chitin + Cu mclaudt 19.01.13 в 10:30 0
	In vitro study shows increased antifungal activity of silver comparing with copper in the same concentration. mclaudt 19.01.13 в 10:31 0
	Fig. 1. Growth dynamic of Alternaria alternata under two different silver and copper ions concentrations. С1 = 25 microg/ml (by metal mass) и С2 = 2.5 microg/ml (by metal mass). mclaudt 19.01.13 в 10:36 0
	Conclusion mclaudt 19.01.13 в 10:36 0
	The interaction with cell wall and the effect on the mechanical properties of its chitin skeleton could take part in antifungal mechanism of silver ions. mclaudt 19.01.13 в 10:39 0
	It correlates with observed low toxicity of silver for animal cells. mclaudt 19.01.13 в 10:41 0

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