Changes in the isozyme composition of antioxidant enzymes in response to aminotriazole in leaves ofArabidopsis thaliana |
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Authors: | Kyong-Suk Kang Chang-Jin Lim Tae-Jin Han Joon-Chul Kim Chang-Duck Jin |
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Institution: | (1) Division of Biology, Kangwon National University, 200-701 Chuncheon, Korea;(2) Department of Biology, Hallym University, 200-702 Chuncheon, Korea |
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Abstract: | The changes in isozyme profiles of catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), and glutathione reductase
(GR) during severe deactivation of total CAT activity by aminotriazole (AT) treatment were investigated in the leaves ofArabidopsis thaliana (Columbia ecotype) in relation to H2O2-mediated oxidative stress. In spite of striking deactivation of total CAT activity by 0.1 mM AT, there were no significant
differences in H2O2 levels or total leaf soluble protein contents including a Rubisco in both the control and AT-treated leaves. On the other
hand, one specific protein band (molecular mass, 66 kD) was observed on the SDS-gel from leaf soluble proteins whose staining
intensity was strikingly enhanced by AT treatment for 6 h. However, this band disappeared at 12 h. In the native-gel assays
of CAT, POD, APX and GR isozymes, AT remarkably inhibited the expression of the CAT1 isozyme with no effects on CAT2 and CAT3,
and generally had no effect on POD isozyme profiles. However, AT stimulated the intensity of activities of pre-existing APX1
and GR1 isozymes. In particular, it induced a new synthesis of one GR isozyme. Therefore, these results collectively suggest
that a striking deactivation of total CAT activity by AT inA. thaliana leaves largely results from the suppression of CAT1 isozyme, and that APX1, GR1, and a newly synthesized GR isozyme could
complement the role of CAT1 to metabolize H2O2 into non-toxic water. |
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Keywords: | aminotriazole antioxidant enzyme Arabidopsis thaliana H2O2 isozyme |
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