The Glutathione S-Transferase (GST) family of isozymes function to detoxify and neutralize a wide variety of electrophilic molecules by mediating their conjugation with reduced glutathione. Human GSTs are encoded by 5 gene families, expressing in almost all tissues as four cytosolic and one microsomal forms. Dividing the family by isoelectric points, the basic alpha (pI 8�11), the neutral mu (pI 5�7) and acidic pi (pH<5) classes are populated by additional subclasses, each isozyme displaying differential specificity for given electrophilic molecules.
Given its pivotal role in ameliorating oxidative stress/damage, GST activity has been repeatedly investigated as a biomarker for arthritis, asthma, COPD, and multiple forms of cancer, as well as an environmental marker. Examination of GST isoforms and activity in human cancers, tumors and tumor cell lines has revealed the predominance of the acidic pi class. Furthermore, this activity is thought to substantially contribute to the innate or acquired resistance of specific neoplasms to anticancer therapy.
The Glutathione S-Transferase (GST) Activity kit is designed to quantitatively measure GST activity in a variety of samples. A GST standard is provided to generate a standard curve for the assay. The kit utilizes non-fluorescent molecule that covalently binds to the free thiol group on GSH, a product of the GST-catalyzed reaction, to yield a highly fluorescent product. After mixing the sample or standard with GSH, the fluorescent substrate and incubating at room temperature, the fluorescent product is read at 460 nm in a fluorescent plate reader with excitation at 390 nm.
Serum, plasma, and cell lysate samples have been validated with this assay.
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