Provided is a compound comprising the structure:

(SIG)-(SI-MOD).sub.m.

In this compound, SIG is a signaling molecule, SI is a self-immolative structure bound to SIG such that SIG has a reduced signal relative to the signal of SIG without SI, MOD is a moiety bound to SI that is subject to modification by an activator, and m is an integer from 1 to about 10. With this compound, when MOD is modified by an activator, SI is destabilized and self-cleaved from SIG such that SIG generates an increased signal. Also provided is a method of determining whether a sample comprises an activator, using the above-described compound. Additionally provided is a method of determining whether a cell comprises a nitroreductase using the above-described compound where nitroreductase is the activator. Further provided is a method of determining whether a mammalian cell is hypoxic using the above-described compound where nitroreductase is the activator. A method of detecting a microorganism that comprises a nitroreductase, using the above-described compound where nitroreductase is the activator, is also provided. Also provided is a method of identifying nitroreductase in a sample, using the above-described compound where nitroreductase is the activator.

The present invention is directed to fluorescent molecular sensor based on Thiazole Orange for protein detection. interaction of the protein target with the molecular sensors of this invention results in a significant increase in the fluorescence emission. The generation of light output signal enables one to detect protein biomarkers associated with different diseases or detecting the protein of interest also in living cells.

The present invention relates to a plasma biomarker for diagnosing hepatocellular carcinoma (HCC), in particular to the discovery of a protein in plasma using 2-D fluorescence differential gel electrophoresis (2-D DIGE), immunoprecipitation and Nano-liquid chromatography mass spectrometry (Nano-LC-MS/MS) system that was unknown on the basis of conventional techniques. By demonstrating the presence of liver carboxylesterase 1 (hCE1) in human plasma and confirming that its secretion level is higher in patients with HCC than in healthy volunteers, this invention may be used as a screening method to diagnose HCC at an early stage.

The invention relates to senescent cell biomarkers and the uses thereof. The invention also extends to methods and kits for detecting senescence, and drug conjugates and pharmaceutical compositions for killing senescent cells.

There is provided a kit that is used for fractionation of cholesterol (lipoprotein C) in a lipoprotein other than small dense LDL in a sample, the kit containing a first reagent composition having at least one activity selected from the group consisting of a cholesterol esterase activity and a cholesterol oxidase activity and a second reagent composition for quantifying the lipoprotein C of a measurement target, where a ratio R1 represented by ABS400/ABS450 is 0.90 or more and 3.50 or less, and in an absorption spectrum after storing the second reagent composition at 37° C. for two weeks, the ratio R1 represented by ABS400/ABS450 is 0.90 or more and 9.00 or less.

The invention relates to senescent cell biomarkers and the uses thereof. The invention also extends to methods and kits for detecting senescence, and drug conjugates and pharmaceutical compositions for killing senescent cells.

Methods for assaying function and/or activity and/or potency of isomerohydrolase proteins are provided.

An apparatus and method for detecting an analyte of interest using paper spray mass spectrometry includes a spray material; a sample on the spray material including an enzyme of interest; a solvent to hydrate the sample, promote enzymatic activity, and extract analytes of interest from the sample; a substrate specific to the enzyme of interest, wherein any of the spray material and the solvent includes the substrate; a voltage source to apply a voltage to the spray material to create charged droplets of a mixture containing the sample; and a mass spectrometer to perform spectrometry on the droplets to perform any of: identify the analytes of interest in the sample; and measure a level of inhibition in any enzymes contained in the sample.

Herein is reported a method for determining the presence of hydrolase activity in a sample by incubating the sample in a buffered solution, which comprises an artificial hydrolase substrate that comprises an ester bond covalently linking an alcohol residue, which is conjugated to a label for removal, and a carboxylic acid residue, which is conjugated to a capture and detection label, as well as bovine serum albumin, and thereafter determining or quantifying, respectively, the released carboxylic acid in the free alcohol depleted incubation mixture.

The present disclosure provides compositions, methods, and kits for detecting lipolytic activity. In some embodiments, the composition comprises an aqueous assay sample and an organic solvent, wherein the organic solvent comprises 4-methylumbellif-erryl caprylate (MU-C8). Also provided herein are methods for determining the stability of a protein preparation.