An apparatus for label-free analysis of molecules, including interactions and reactions of the molecules, is disclosed. The apparatus is based on detecting molecule movement under the influence of an external electric field. The apparatus is able to achieve sensitive detection of molecular binding to proteins or other molecules, and conformational changes of proteins or other molecules and biochemical reactions of the proteins or other molecules. Applications of the apparatus include screening of drug molecules, kinetic analysis of posttranslational modification of proteins, and small molecule-protein interactions.

The present invention is directed to a method of measuring the dissociation rate of the binding of an antibody to an antigen. The method has two phases: a first phase of binding and a second phase of dissociation. The first phase of the assay has a probe coated with an antigen, or protein G, or an anti-human IgG Fc antibody. The probe is immersed in a sample solution containing an antibody, followed by a wash sequence, then the probe is transferred to a reagent with a biotinylated antigen. After an incubation, the antibody bound on the probe binds to the biotinylated antigen to form an immune complex. Fluorescent signal is produced by immersing the probe in a reagent having a fluorescent tagged streptavidin. The last step of the first phase is a measurement of fluorescent on the probe tip. The second phase of the assay is making subsequent fluorescent measurements over time to monitor the loss in fluorescence indicating dissociation of the immune complex and calculating the dissociation rate of the binding of the antibody to the antigen.

The present invention is directed to a method of measuring the dissociation rate of the binding of an antibody to an antigen. The method has two phases: a first phase of binding and a second phase of dissociation. The first phase of the assay has a probe coated with an antigen, or protein G, or an anti-human IgG Fc antibody. The probe is immersed in a sample solution containing an antibody, followed by a wash sequence, then the probe is transferred to a reagent with a biotinylated antigen. After an incubation, the antibody bound on the probe binds to the biotinylated antigen to form an immune complex. Fluorescent signal is produced by immersing the probe in a reagent having a fluorescent tagged streptavidin. The last step of the first phase is a measurement of fluorescent on the probe tip. The second phase of the assay is making subsequent fluorescent measurements over time to monitor the loss in fluorescence indicating dissociation of the immune complex and calculating the dissociation rate of the binding of the antibody to the antigen.

The invention provides a method of measuring the affinity of first and second biomolecules in which a first biomolecule is tethered by a first tether portion having a first tether portion length and a second biomolecule is tethered by a second tether portion having a second tether portion length, the method comprising determining binding of adjacent first and second biomolecules to each other, varying at least one of the first and second tether lengths and determining binding of the first and second biomolecules. The invention also provides apparatus suitable for use in the method of the invention.

The invention provides a method of measuring the affinity of first and second biomolecules in which a first biomolecule is tethered by a first tether portion having a first tether portion length and a second biomolecule is tethered by a second tether portion having a second tether portion length, the method comprising determining binding of adjacent first and second biomolecules to each other, varying at least one of the first and second tether lengths and determining binding of the first and second biomolecules. The invention also provides apparatus suitable for use in the method of the invention.

Provided herein are methods and systems allowing for real-time measurement of cellular drug-target engagement. Use of fluorescence-based cell target engagement technology with real-time gene expression machinery provides several advantages over prior systems. Integration with real-time gene expression machinery without bias to any particular design or brand is provided. Programmability of cell target engagement methodology, such that any software in real-time gene expression machine can seamlessly be used for programming is provided. Single or multiple machine integration for the use of cell target engagement technology is provided. Compatibility with multiple multi-well plate setups is provided. Development of unique modifications of real-time (quantitative) gene expression software to detect real-time cellular drug-target engagement to work efficiently with existing gene expression machinery is provided.

Provided herein are methods and systems allowing for real-time measurement of cellular drug-target engagement. Use of fluorescence-based cell target engagement technology with real-time gene expression machinery provides several advantages over prior systems. Integration with real-time gene expression machinery without bias to any particular design or brand is provided. Programmability of cell target engagement methodology, such that any software in real-time gene expression machine can seamlessly be used for programming is provided. Single or multiple machine integration for the use of cell target engagement technology is provided. Compatibility with multiple multi-well plate setups is provided. Development of unique modifications of real-time (quantitative) gene expression software to detect real-time cellular drug-target engagement to work efficiently with existing gene expression machinery is provided.

In one aspect, the present invention provides a method of selecting or identifying an agent that inhibits a target protein having an active site. In another aspect, the invention provides a method of selecting an agent that inhibits a target protein having an active site for further optimization. In some embodiments, the methods comprise measuring or predicting stability of an induced fit conformation of an agent contacted to an active site of the protein, wherein the agent is selected if the stability of the induced fit conformation of the agent contacted to the active site of the protein is increased relative to a reference stability.

Methods of isolating and purifying hematologic or non-hematologic tumor cells useful in a variety of assays and procedures, including tumor drug efficacy screening such as Microculture Kinetic assays, are disclosed herein. Further, Microculture Kinetic assays and methods suitable for comparing the relative efficacy of generic versus proprietary anti-cancer drugs are also disclosed.

Methods of isolating and purifying hematologic or non-hematologic tumor cells useful in a variety of assays and procedures, including tumor drug efficacy screening such as Microculture Kinetic assays, are disclosed herein. Further, Microculture Kinetic assays and methods suitable for comparing the relative efficacy of generic versus proprietary anti-cancer drugs are also disclosed.