Journal article
Purification and characterization of a glutathione S-transferase from benoxacor-treated maize (Zea mays)
Plant physiology (Bethesda), Vol.102(3), pp.803-810
07/1993
Handle:
https://hdl.handle.net/2376/117617
PMCID: PMC158850
PMID: 8278534
Abstract
A glutathione S-transferase (GST) isozyme from maize (Zea mays Pioneer hybrid 3906) treated with the dichloroacetamide herbicide safener benoxacor (CGA-154281) was purified to homogeneity and partially characterized. The enzyme, assayed with metolachlor as a substrate, was purified approximately 200-fold by ammonium sulfate precipitation, anion-exchange chromatography on Mono Q resins, and affinity chromatography on S-hexylglutathione agarose from total GST activity present in etiolated shoots. The purified protein migrated during sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) as a single band with a molecular mass of 27 kD. Using nondenaturing PAGE, we determined that the native protein has a molecular mass of about 57 kD and that the protein exists as a dimer. Two-dimensional electrophoresis revealed only a single protein with an isoelectric point of 5.75 and molecular mass of 27 kD. These results further suggest that the protein exists as a homodimer of two identical 27-kD subunits. The enzyme was most active with substrates possessing a chloroacetamide structure. trans-Cinnamic acid and 1-chloro-2,4-dinitrobenzene were not effective substrates. Apparent Km values for the enzyme were 10.8 microM for the chloroacetamide metolachlor and 292 microM for glutathione. The enzyme was active from pH 6 to 9, with a pH optimum between 7.5 and 8. An apparently blocked amino terminus of the intact protein prevented direct amino acid sequencing. The enzyme was digested with trypsin, and the amino acid sequences of several peptide fragments were obtained. The sequence information for the isolated GST we have designated "GST IV" indicates that the enzyme is a unique maize GST but shares some homology with maize GSTs I and III.
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Details
- Title
- Purification and characterization of a glutathione S-transferase from benoxacor-treated maize (Zea mays)
- Creators
- G P Irzyk - Department of Crop and Soil Sciences, Washington State University, Pullman 99164-6420E P Fuerst - Department of Crop and Soil Sciences, Washington State University, Pullman 99164-6420
- Publication Details
- Plant physiology (Bethesda), Vol.102(3), pp.803-810
- Academic Unit
- Crop and Soil Sciences, Department of
- Identifiers
- 99900548582101842
- Language
- English
- Resource Type
- Journal article