Abstract: Methods and compositions are provided for assaying for enzymes capable of releasing an enzyme donor fragment (ED) conjugated to a nucleic acid strand bonded to a surface. Conveniently, the beads are magnetic allowing segregation of the beads during the determination. Upon addition of enzyme acceptor fragment (EA) and substrate to the assay mixture, the method allows for discrimination between ED free in solution and ED bound to the bead. The complexing of ED and EA provides an active ?-galactosidase enzyme. The method permits the assay of any substance involved in a pathway that can result in a reaction releasing the ED.

Abstract: Methods and reagents are provided for measuring protease activity. The reagent comprises a surface to which is linked an enzyme donor fragment through a protease recognition sequence, where the enzyme donor fragment complexes with an enzyme acceptor fragment to form an active indicator enzyme when the enzyme donor fragment is cleaved from said surface. Conveniently, the surface is a cell membrane surface where the reagent is expressed in the cell. The method comprises bringing together the reagent, the protease, the enzyme acceptor and substrate for the indicator enzyme and measuring the indicator enzyme activity as a measure of the protease activity. The method finds application in screening for compounds modulating the activity of the protease.

Abstract: A protein reagent is provided for measuring protease enzyme activity in a sample. The protein reagent comprises two inhibition entities joined by a linker comprised of an indicator enzyme donor and an amino acid sequence susceptible to enzymatic cleavage. The protein reagent is substantially inhibited from binding to the cognate enzyme acceptor fragment, while the product of the enzymatic cleavage binds to the cognate enzyme acceptor fragment to form a functional indicator enzyme. The indicator enzyme activity is related to the protease enzyme activity of the sample.

Abstract: Methods and reagents are provided for measuring protease activity. The reagent comprises a surface to which is linked an enzyme donor fragment through a protease recognition sequence, where the enzyme donor fragment complexes with an enzyme acceptor fragment to form an active indicator enzyme when the enzyme donor fragment is cleaved from said surface. Conveniently, the surface is a cell membrane surface where the reagent is expressed in the cell. The method comprises bringing together the reagent, the protease, the enzyme acceptor and substrate for the indicator enzyme and measuring the indicator enzyme activity as a measure of the protease activity. The method finds application in screening for compounds modulating the activity of the protease.

Abstract: A protein reagent is provided for measuring protease enzyme activity in a sample. The protein reagent comprises two inhibition entities joined by a linker comprised of an indicator enzyme donor and an amino acid sequence susceptible to enzymatic cleavage. The protein reagent is substantially inhibited from binding to the cognate enzyme acceptor fragment, while the product of the enzymatic cleavage binds to the cognate enzyme acceptor fragment to form a functional indicator enzyme. The indicator enzyme activity is related to the protease enzyme activity of the sample.

Abstract: Formation of an intramolecular cross-link in enzyme donor polypeptide fragments of .beta.-galactosidase, thereby forming a cyclic enzyme donor which is hindered from complementation with an enzyme acceptor fragment to form active of .beta.-galactosidase. The cyclic enzyme donor can be linearized by cleaving to restore complementation ability. Assays in which such cyclic enzyme donors are linearized by specific analytes are disclosed, as well as novel homobifunctional bis-maleimido cross-linking agents of the formula ##STR1## wherein R is hydroxy or acetate.

Abstract: Simplified calibration and improved dose-response linearity of the standard curve of competitive assays are obtained by adding a predetermined amount of unlabeled competitive binding compound (usually just the analyte itself) to a first reagent containing anti-analyte antibodies before the reagent is reacted with a sample containing an unknown amount of analyte.

Abstract: Formation of an intramolecular cross-link in enzyme donor polypeptide fragments of .beta.-galactosidase, thereby forming a cyclic enzyme donor which is hindered from complementation with an enzyme acceptor fragment to form active of .beta.-galactosidase. The cyclic enzyme donor can be linearized by cleaving to restore complementation ability. Assays in which such cyclic enzyme donors are linearized by specific analytes are disclosed, as well as novel homobifunctional bis-maleimido cross-linking agents of the formula ##STR1## wherein R is hydroxy or acetate.

Abstract: A method and device for determining the presence of an analyte in a sample suspected of containing the analyte is disclosed. The method involves contacting a test solution containing the sample and a first member of a specific binding pair with an end portion of a strip of bibulous material capable of being traversed by the test solution through capillary action. The first member of a specific binding pair is capable of binding the analyte. The strip contains a second member of a specific binding pair integral therewith for concentrating and non-diffusively binding the first sbp member at a small situs on the strip separated from the end portion of the strip. The detectible signal is produced in relation to the presence of the analyte in the test solution. The test solution passes through the situs as the test solution traverses the bibulous material.

Abstract: A method for reducing or eliminating tyramine interference from amphetamine and methamphetamine immunoassays, comprising treating the sample with aqueous tyramine oxidase for a time and at a temperature and pH sufficient to deaminate any tyramine present in the sample, is provided.

Abstract: Galactopyranoside derivative compounds for use as substrates for hydrolysis by enzymes with .beta.-galactosidase activity are provided. The concentration of the reaction products can be measured by spectroscopy. The compounds find particular use in diagnostic assays for detection of analyte.

Abstract: Galactopyranoside derivative compounds for use as substrates for hydrolysis by enzymes with .beta.-galactosidase activity are provided. The concentration of the reaction products can be measured by spectroscopy. The compounds find particular use in diagnostic assays for detection of analyte.

Abstract: Compounds are evaluated for their binding to naturally occurring receptors, by employing the natural ligand conjugated to an enzyme donor fragment of .beta.-galactosidase for competing with the sample compound for the natural acceptor binding site or in the absence of competition where the sample compound binds to an allosteric site. By adding the enzyme acceptor fragment of the .beta.-galactosidase and substrate, the binding affinity of the sample compound may be evaluated as a measure of agonist or antagonist capability.

Abstract: The present invention provides reagents for a detectable label for use in specific binding assays. Specifically, modified .beta.-galactosidase enzyme donors (ED) and acceptors (EA) are utilized. Both ED and EA are modified to form separate ED and EA complexes by coupling each with a linking element and a binding moiety which is specific to a binding site in the analyte. The ED and EA complexes are incapable of forming active enzyme in the absence of the analyte. However, when analyte is present, ED and EA complexes which bind to a common analyte in a sample, active .beta.-galactosidase is formed.

Abstract: Enzyme-donor fragments and other unstructured peptides are stabilized against proteolytic degradation by including a mixture of soluble, random-sequence peptides in the assay medium or in the medium in which the enzyme-donor fragment or other peptide is stored.

Abstract: A device is disclosed for conducting an assay method. The device comprises a housing, means enclosed in the housing for capturing a member of a specific binding pair in a zone and for allowing liquid to be transported by capillary action away from the zone, one or more self-contained liquid reagents enclosed in the housing for conducting an assay method for the determination of an analyte in the sample, and means in the housing for introducing the sample into the device. Preferably, the self-contained reagents are liquid reagents which are contained in a breakable container. The device of the invention finds use in assay methods for the determination of an analyte in a sample suspected of containing the analyte. Kits for conducting an assay method are also disclosed.

Abstract: Carbonyl derivatives of acetaminophen are provided for use in homogeneous enzyme immunoassays for acetaminophen. The derivatives are conjugated to antigenic substances for the preparation of antisera specific to acetaminophen, and to enzymes for the preparation of enzyme conjugates which compete with acetaminophen for antibody binding sites in a typical assay.

Abstract: Serum is passed through a column containing silica gel alkylated with lower alkyl groups. The column is then washed with dilute acid and water and the digoxin eluted with aqueous methanol at a volume less than about the volume of the serum to provide a digoxin concentrate that may be used in assay determinations. The invention also includes a kit comprising in a packaged combination for use in an assay for digoxin (a) a column containing silica gel alkylated with alkyl groups containing 1 to 2 carbon atoms and (b) an aqueous eluent solution which is 50%-70% by volume organic solvent. The organic solvent comprises from 1-4 carbon atoms and from 1-3 heteroatoms selected from the group consisting of oxygen and nitrogen.

Abstract: Methods and kits are provided for detecting analytes, which can be measured directly or indirectly, by production of an enzymatic product. The enzymatic product reacts with a signal producing reagent bound to a bibulous strip. Various devices are employed for producing a reaction, directly or indirectly, with the analyte and then providing for migration of the product through the bibulous strip with reaction with the reagent to produce a detectable signal. The distance from a pre-determined site to the border of the detectable signal is a quantitative measure of the analyte in the sample.

Abstract: A method and device for determining the presence of an analyte in a sample suspected of containing the analyte is disclosed. The method involves contacting a test solution containing the sample and a first member of a specific binding pair with an end portion of a strip of bibulous material capable of being traversed by the test solution through capillary action. The first member of a specific binding pair is capable of binding the analyte. The strip contains a second member of a specific binding pair integral therewith for concentrating and non-diffusively binding the first sbp member at a small situs on the strip separated from the end portion of the strip. The detectible signal is produced in relation to the presence of the analyte in the test solution. The test solution passes through the situs as the test solution traverses the bibulous material.