• Sensitive - Measures < 10 mU/mL of GST Activity.
• Convenient - Stable, 4 ºC liquid reagents.
• Flexible - Can be used for kinetic or end point measurement.
• Selective - Limited interference from solvents, detergents or bilirubin.
• Can detect Glutathione S-Transferase activity in biological samples such as serum, plasma, urine and cell lysates.

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 glutathione1. 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 molecules². 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^3-7. 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^8,9.

The Fluoro GST Kit is designed to quantitatively measure the activity of GST present in a variety of samples. Please read the complete kit insert before performing this assay. A GST standard is provided to generate a standard curve for the assay and all samples should be read off the standard curve. The kit utilizes a non-fluorescent molecule that is a substrate for the GST enzyme that covalently attaches to glutathione (GSH) to yield a highly fluorescent product. Mixing the sample or standard with the supplied Detection Reagent and GSH and incubating at room temperature for 30 minutes yields a fluorescent product that is read at 460 nm in a fluorescent plate reader with excitation at 390 nm. The activity of the GST in the sample is calculated, after making a suitable correction for any dilution of the sample, using software available with most fluorescence plate readers.

We have provided a 96 well plate for measurement but this assay is adaptable for higher density plate formats. The end user should ensure that their HTS black plate is suitable for use with these reagents prior to running samples.

The Fluoro GST Kit is designed to Detect Glutathione S-Transferase activity in biological samples such as serum, plasma, urine and cell lysates.

1. Habig, W, et al. “Glutathion S-Transferases: The First Enzymatic Step in Mercapturic Acid Formation” J. Biol.Chem. 1974 249(22):7130-7139.
2. Cook, JA, et al., “Differential Specificity of Monochlorobimane for Isozymes of Human and Rodent Glutathione S-Transferases” Cancer Res. 1991 51:1606-1612.
3. Dalle-Donne, I, et al. “Biomarkers of Oxidative Damage in Human Disease” Clinical Chemistry, 2006 52(4):601-623.
4. Surapneni, KM & VSC Gopan, “Lipid Peroxidation and Antioxidant Status in Patients with Rheumatoid Arthritis” ¨Ind.J.Clin.Biochem. 2008 23(1):41.44.
5. Mohan, SK & O Venkataramana. “Status of Lipid Peroxidation, Glutathione, Ascorbic Acid, Vitamin E and Antioxidant Enzymes in Patients with Osteoarthritis” Ind.J.Med. Sci.¨ 2007 61:9-14.
6. Ferrandina, G., et al., “Glutathione S-Transferase Activity in Epithelial Ovarian Cancer: Association with Response to Chemotherpapy and Disease Outcome” Ann.Oncol. 1997 8:343-350.
7. Otitoju, O & Onwarah, INE. “Glutathione S-transferase (GST) Activity as a Biomarker in Ecological Risk Assessment of Pesticide Contaminated Environment” African J. Biotech. 2007 6(12)1455-1459.
8. Shea, TC, et al., “Identification of an Anionic Form of Glutathione Transferase Present in Many Human Tumors and Human Tumor Cell Lines” Cancer Res. 1988 48:527-533.
9. Shea, TC, et al., “Glutathione Transferase Activity and Isozyme Composition in Primary Human Breast Cancers” Cancer Res. 1990 50:6848-6853.