This non radioactive colorimetric assay kit uses a 96 well format, and all the necessary reagents are supplied for measuring enzyme activity and are ideal for high throughput drug screening. Colorimetric assays for GTPases are invariably based on the formation of colored complexes between an inorganic phosphate and a dye molecule under acidic conditions. Such assays are beset with problems of reagent precipitation and high backgrounds caused by impure substrates (i.e. contaminated with inorganic phosphate) and/or by non-enzymatic (acid) hydrolysis of the substrate. At the heart of our assay kits is PiColorLock Gold, a superior phosphate detection reagent which ensures high stability of the colored dye-phosphate complexes. Together with specially purified substrates and proprietary stabilizers our kits offer the lowest possible assay backgrounds and outstanding assay performance. Uniquely, Innova Biosciences GTPase assay kits contain highly purified GTP, which have had any free inorganic phosphate removed ® this means that assays have the lowest possible background signal. PiColorLock reagent may also be purchased separately for developing simple assays for any phosphate-generating enzyme. It is offered in both high (Gold) and standard sensitivity (ALS) formulations to suit almost any assay situation.