Abstract: A method and kit is provided for enhancing the tolerance of an assay reagent to compounds in an assay sample, the assay reagent including a luciferase enzyme. The method includes contacting the luciferase with a tolerance enhancement agent in an amount sufficient to substantially protect luciferase enzyme activity from interference of the compound and minimize interference by at least about 10% relative to an assay not having tolerance enhancement agent.

Abstract: Kits and peptide substrates for detecting transferase activity of a sample are provided. The kits include a substrate including a reporter compound, at least one of a phosphate group donor and a phosphate group acceptor, a buffer that supports enzymatic activity of the transferase, and a peptidase that cleaves a non-phosphorylated peptide substrate at a first rate and a phosphorylated peptide substrate at a second rate. The peptide substrates include a reporter compound and a first transferase substrate linked to the reporter compound on a first side of the reporter compound.

Abstract: A method for detecting transferase activity of a sample includes contacting the sample with a substrate and at least one of a phosphate group donor and a phosphate group acceptor. The substrate includes a reporter compound and amino acids. A peptidase is added that cleaves a non-phosphorylated substrate at a first rate and a phosphorylated substrate and a second rate. The output of the reporter compound is detected. In a preferred embodiment, the transferase activity detected is a kinase activity. In another preferred embodiment, the transferase activity detected is a phosphatase activity. Also provided is a method of screening for alterations in a transferase reaction. Kits and peptide substrate are also provided for carrying out at least one of the methods of the invention.

Abstract: A mutant hydrolase optionally fused to a protein of interest is provided. The mutant hydrolase is capable of forming a bond with a substrate for the corresponding nonmutant (wild-type) hydrolase which is more stable than the bond formed between the wild-type hydrolase and the substrate. Substrates for hydrolases comprising one or more functional groups are also provided, as well as methods of using the mutant hydrolase and the substrates of the invention. Also provided is a fusion protein capable of forming a stable bond with a substrate and cells which express the fusion protein.

Abstract: A method for detecting transferase activity of a sample includes contacting the sample with a substrate and at least one of a phosphate group donor and a phosphate group acceptor. The substrate includes a reporter compound and amino acids. A peptidase is added that cleaves a non-phosphorylated substrate at a first rate and a phosphorylated substrate and a second rate. The output of the reporter compound is detected. In a preferred embodiment, the transferase activity detected is a kinase activity. In another preferred embodiment, the transferase activity detected is a phosphatase activity. Also provided is a method of screening for alterations in a transferase reaction. Kits and peptide substrate are also provided for carrying out at least one of the methods of the invention.

Abstract: A method for detecting transferase activity of a sample includes contacting the sample with a substrate and at least one of a phosphate group donor and a phosphate group accepto. The substrate includes a reporter compound and amino acids. A peptidase is added that cleaves a non-phosphorylated substrate at a first rate and a phosphorylated substrate and a second rate. The output of the reporter compound is detected. In a preferred embodiment, the transferase activity detected is a kinase activity. In another preferred embodiment, the transferase activity detected is a phosphatase activity. Also provided is a method of screening for alterations in a transferase reaction. Kits and peptide substrate are also provided for carrying out at least one of the methods of the invention.

Abstract: A mutant hydrolase optionally fused to a protein of interest is provided. The mutant hydrolase is capable of forming a bond with a substrate for the corresponding nonmutant (wild-type) hydrolase which is more stable than the bond formed between the wild-type hydrolase and the substrate. Substrates for hydrolases comprising one or more functional groups are also provided, as well as methods of using the mutant hydrolase and the substrates of the invention. Also provided is a fusion protein capable of forming a stable bond with a substrate and cells which express the fusion protein.

Abstract: A method for detecting transferase activity of a sample includes contacting the sample with a substrate and at least one of a phosphate group donor and a phosphate group acceptor. The substrate includes a reporter compound and amino acids. A peptidase is added that cleaves a non-phosphorylated substrate at a first rate and a phosphorylated substrate and a second rate. The output of the reporter compound is detected. In a preferred embodiment, the transferase activity detected is a kinase activity. In another preferred embodiment, the transferase activity detected is a phosphatase activity. Also provided is a method of screening for alterations in a transferase reaction. Kits and peptide substrate are also provided for carrying out at least one of the methods of the invention.