þÿ<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><head><meta name=Titelcontent="JBPC Vol. 6, 1, 2006 ABSTRACT"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>JBPC Vol. 6, 2, 2006 ABSTRACT </title></head> <body link="#0000FF"><center><h1><font color="#006600">The Journal of Biological Physics and Chemistry</font></h1></center> <p></p><p></p> <b><center>2006<p>Volume 6, Number 2, p.p. 71-76</center></b> <br> <div> <p><b><font size=+2> Does polyphenol oxidase catalyse the primary hydroxylation of absorbed benzene in tea leaves? </font></b></p> <p> <b> D. Ugrekhelidze<sup>1</sup> and Ugrekhelidze<sup>2</sup> </b> <br><br> <i> <sup>1</sup> Institute of Biochemistry and Biotechnology, Georgian Academy of Sciences, Digomi, 0059 Tbilisi, Georgia <br> <sup>2</sup> Georgian National Centre of High Technologies, 21 Kavtaradze St, 0086 Tbilisi, Georgia </i> </p> <p> The assimilation of [1-614C]-benzene vapour by tea seedlings has been studied. Benzene assimilation by leaves is stimulated by light, and as a result of assimilation, the products of cleavage of the aromatic ring (organic acids), and also products of complete oxidation, 14CO2, are formed. The percentage distribution of carbon atoms of [1-614C]-benzene in cellular organelles in tea leaves shows that the label is localized mainly in chloroplasts and the cytosol. The total enzyme preparation from leaves oxidizes benzene, and the oxidation process is strongly stimulated by o-dihydroxyphenols (10 3 M). 8-oxyquinoline (10 3 M) or sodium diethyldithiocarbamate (10 3 M) strongly inhibits benzene oxidation, and the effect of ±,± 2-dipyridyl (10 3 M) is low. Partially purified polyphenol oxidase from tea leaves also oxidizes benzene. The process of oxidation is very strongly stimulated by pyrocatechol, chlorogenic acid and d-catechin (10 3 M), and as an intermediate product phenol is formed. It is posited that the hydroxylation process is catalysed by copper-containing enzymes, mainly by the phenol oxidases localized in chloroplasts.</p> <b>Keywords: </b> benzene hydroxylation, polyphenol oxidase, <i>Thea sinensis</i>, xenobiotics <br></div><p></p> <center><p><i><font size=-1><a href="jbpc20606.html">back to contents</a></font></i></p></center> </body></html>