Atrazine transferases

Anderson, M.R and J.W. Gronwald (1991). Atrazine resistance in a velvetleaf (Abutilon theophrasti) biotype due to enhanced glutathione 5-transferase activity. Plant Physiol., 96 104-109. 

Although no specific metabolites have been identified, atrazine has been shown to turnover cytosolic glutathione 5-transferase indicating conjugation in zebrafish, rainbow trout, starry flounder (.Platichthys stellatus) and English sole (.Pleuronectes vetulus)22,90. Approximately 50% of atrazine was converted to four uncharacterized metabolites in zebrafish36. 

Glutathione S-transferase enzymes have been detected In a variety of different plant species (24,76.64.97.101.107-110). Howevei, detailed enzyme studies have been limited to corn (24.76, J09., 12 ) and pea (. JOT., 110). The foliar tissue of corn contains a GST Isozyme that appears rather unique In Its ability to catalyze the conjugation of various 2-chloro-s-trlazlnes with GSH (78). The molecular weight and other properties of this Isozyme are similar to those reported for many mammalian GST Isozymes however, the pH optimum of this Isozyme for atrazine Is somewhat lower than that reported for many GST Isozymes (, 78,J09.). When corn Is treated with R-25788, a second Isozyme Is Induced ( ). The Induced Isozyme Is very effective In catalyzing the GSH conjugation of an a-chloroacetamlde herbicide (alachlor), but It was not assayed with atrazine ( ). 

Table 9.4 Specific Activity of Glutathione Transferase Isolated from Atrazine-Resistant (R) and -Susceptible (S) Biotypes of Velvetleaf (Abutilon theophrasti)...

Another common resistance mechanism is enhanced detoxication in plants. Atrazine has an electrophilic carbon that may be attacked by glutathione, and biotypes of various weeds may have glutathione transferases that have a better ability to catalyze this reaction ... 

Plaisance, K.L. and Gronwald, J.W. 1999. Enhanced catalytic constant for glutathione S-transferase (atrazine) activity in an atrazine-resistant Abutilon theophrasti biotype. Pest. Biochem. Physiol., 63, 34-49. 

Measured as nmol GS-atrazine produced per hour and mg of purified glutathione transferase. 

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