Документ взят из кэша поисковой машины. Адрес оригинального документа : http://mgumus.chem.msu.ru/publication/2005/davidchik-laccase-05.pdf Дата изменения: Thu Jul 21 15:07:26 2005 Дата индексирования: Mon Oct 1 20:45:56 2012 Кодировка:

CHEMISTRY FACULTY OF M.V.LOMONOSOV MOSCOW STATE UNIVERSITY MINISTRY OF EDUCATION AND SCIENCE RUSSIAN FEDERATION RUSSIAN FOUNDATION FOR BASIC RESEARCH N.M.EMMANUEL INSTITUTE OF BIOCHEMICAL PHYSICS OF RUSSIAN ACADEMY OF SCIENCES MOSCOW STATE UNIVERSITY INTERNATIONAL BIOTECHNOLOGY CENTER RESEARCH INSTITUTE OF PURE BIOCHEMICALS ZAO "BioChimMac" GROUP OF COMPANIES "BIOPROCESS"

INTERNATIO NAL CO NFERENC E

INTERNATIONAL CONFERENCE

B C - 2005
B IO CATALYS IS: FUNDAMENTALS & AP PLICATIO NS

BIOCATALYSIS-2005:
FUNDAMENTALS & APPLICATIONS
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ORGANIZING COMMITTEE
Chairman: Prof. S.Varfolomeev Scientific Secretary: Dr. T.Osipova Members: Dr. N.Eremeev Prof. A.Gabibov Dr. S.Kurzeev Dr. E.Zaitseva Dr. P.Binevskii Dr. G.Kazankov Prof. V.Tishkov E. Sadykhov

PROGRAMME COMMITTEE
Chairman: Prof. V.Tishkov Members: Prof. A.Gabibov Prof. A.Maximenko Prof. A.Levashov Prof. I.Kurochkin Prof. S. Kalyuzhnyi Prof. V.Svedas

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©2005, Department of Chemical Enzymology, The M.V.Lomonosov Moscow State University

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LACCASE-MEDIATED TRANSFORMATION OF ATRAZINE IN THE ENVIRONMENT Valentina N. Davidchik 1, Natalia A. Kulikova 2, Elena V. Stepanova 1, Olga V. Koroleva 1
1

A.N. Bach Institute of Biochemistry, Moscow, Russia; E-mail: vdavidchik@gmail.com 2 M.V. Lomonosov Moscow State University, Moscow, Russia

Laccase ( 1.10.3.2) is a unique extracellular multicopper oxidase which activity can be determined in soils annually. Laccase can oxidize different aromatic compounds, such as phenols, anilines, etc. Substrate specificity of enzyme can be considerably expanded using redox mediators. The introduction of redox-mediators in system containing xenobiotic and enzyme allows transforming compounds that initially do not oxidized by laccase. Laccase is therefore considered to be a promising enzyme for application in biotechnology, especially for enzymatic treatment of the contaminated soils. This study was aimed to investigate the mechanisms of transformation of widely used persistent herbicide atrazine in different natural environments in the presence of laccase from Coriolus hirsutus. The initial step of this research was to evaluate sorption capacity of soil particles towards atrazine. The data of atrazine sorption on soil particles have been assessed in terms of xenobiotic distribution coefficient (Kd). Three soils including chernozem, grey forest and sod-podzolic soils were used in this study. The sampled soils were characterized according to standard protocol. Atrazine concentration in reaction mixture varied in the range 1 to 10 mg/l; concentration of laccase was 6.4 10-8 M. Atrazine concentrations were determined using HPLC. The highest atrazine adsorption capacity was observed for sod-podzolic soil (Kd = 1.9 L/kg), whilst Kd values for chernozem and gray forest soil were determined as 1.4 and 0.4 L/kg, respectively. Introduction of laccase resulted in increase of Kd values for all the studied soils. The greatest effect of laccase on atrazine adsorption was registered for grey forest soil (Kd = 1.1 L/kg), whereas for sod-podzolic soil (Kd = 2.5 L/kg) and chernozem (Kd = 1.7 L/kg) that was less pronounced. The experiments on desorption revealed that atrazine adsorption onto soil particles was partly reversible. In the presence of laccase, however, desorption was considerably low, probably due to chemisorption process. As there was no atrazine binding to laccase under selected experimental conditions, the enzyme was hypothesized to catalyse and/or initiate the process of atrazine transformation via mechanism of oxidative coupling. Laccase interaction with humic acids was previously shown to be of complex nature that affects the process of atrazine transformation. The study of atrazine adsorption process on soil particles has confirmed the assumption about xenobiotic chemisorption as the increase of atrazine adsorption in the presence of laccase on all examined soil samples was observed presumably via the mechanism of oxidative coupling.
The research was supported by RFBR ( 04-04-49679, 03-04-49180).

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