Abstract: An aqueous, liquid-stable thiol activator solution is disclosed. The solution can include a thiol activator, such as N-acetyl-L-cysteine and a stabilizing agent, such as mannitol. The thiol is stabilized in the aqueous solution for at least about one year under storage conditions and for at least about 28 days under open-bottle conditions. The solution can be used as a reactivator of creatine kinase catalytic activity.

Abstract: A method for the cell-free synthesis and isolation of novel genes and polypeptides is provided. Within one embodiment, an expression unit is constructed onto which semi-random nucleotide sequences are attached. The semi-random nucleotide sequences are first transcribed to produce RNA, and then translated under conditions such that polysomes are produced. Polysomes which bind to a substance of interest are then isolated and disrupted; and the released mRNA is recovered. The mRNA is used to construct cDNA which is expressed to produce novel polypeptides.

Abstract: Enzyme activity is measured promptly with a high accuracy by introducing an enzyme, the activity of which is to be measured, into a column comprising a hollow tube packed with a filler comprising a support and a substrate that can be recognized by the enzyme, which is immobilized on the support, and measuring the amount of the obtained decomposition product of the substrate.

Abstract: A reagent for assaying glucose, which comprises a first liquid reagent having a pH of 7.5 to 9.5 and containing at least either glucokinase or hexokinase, glucose 6-phosphate dehydrogenase, and adenosine 5'-triphosphate and a second liquid reagent having a pH of 3 to 5 and containing the oxidized form of nicotinamide adenine dinucleotide phosphate. The reagent can be stored as such stably for long in or out of contact with light at normal or low temperatures, so that it can be stored for long in the site of clinical examination and applied to an automatic analyzer without the necessity for dissolution prior to use.

Abstract: The present invention is directed to the assay and purification of proteins, and particularly to the non-radioactive assay and purification of protein kinases, phosphatases and protease by incubating the enzyme with a substrate modified peptide to form a product modified peptide under conditions where the enzyme is active. The product modified peptide and substrate modified peptide are then separated, and the product modified peptide is measured. The present invention is also directed to kits and bioreagents for performing the assays.

Abstract: The method is directed to assaying for biological components in a sample comprising step (A) generating an oxidase substrate in the presence of an amphoteric surfactant and in the absence of ferrocyanide; (B) initially generating hydrogen peroxide through said oxidase reaction on said substrate of oxidase with subsequent detection of the generated hydrogen peroxide using peroxidase and a color developer capable of being oxidized in the presence of amphoteric surfactant and ferrocyanide; and (C) correlating the amount of color developed to the amount of biological components in the biological sample. Even when the biological component to be detected is present in a very small amount, the interference of bilirubin can be eliminated in assays of biological components in which peroxidase generated from an enzymatic reaction is detected using peroxidase and a color developer capable of being oxidized.

Abstract: Enzymatically clearable chemiluminescent 1,2-dioxetane compounds capable of producing light energy when decomposed, substantially stable at room temperature before a bond by which an enzymatically clearable labile substituent thereof is intentionally cleaved, are disclosed. These compounds can be represented by the formula: ##STR1## wherein: X and X.sup.1 each represent, individually, hydrogen, a hydroxyl group, a halo substituent, an unsubstituted lower alkyl group, a hydroxy (lower) alkyl group, a halo (lower) alkyl group, a phenyl group, a halophenyl group, an alkoxyphenyl group, a hydroxyalkoxy group, a cyano group or an amide group, with at least one of X and X.sup.1 being other than hydrogen; and R.sub.1 and R.sub.2, individually or together, represent an organic substituent that does not interfere with the production of light when the dioxetane compound is enzymatically cleaved and that satisfies the valence of the dioxetane compound's 4-carbon atom, with the provisos that if R.sub.1 and R.sub.

Abstract: A measuring composition for use in determination of glucose, ATP, phosphotransferases such as creatine phosphokinase, and glucosidases is disclosed. The composition is comprised of glucokinase, glucose-6-phosphate dehydrogenase, and potassium or ammonium ions. This composition makes it possible to shorten measuring times even if the amount of enzyme is reduced, and exhibits high stability when stored at room temperature in a solution state.

Abstract: A method is provided for determining glucose-6-phosphate, including the step of dehydrogenating glucose-6-phosphate and NAD or NADP in the presence of glucose-6-phosphate dehydrogenase to produce 6-phosphogluconate and NADH or NADPH, wherein the determination is carried out in the presence of 6-phosphogluconolactonase. Also provided is a composition for determining glucose-6-phosphate, characterized by containing 6-phosphogluconolactonase, glucose-6-phosphate dehydrogenase, and NAD or NADP.

Abstract: The invention concerns a new 6-phosphogluconolactonase which has an enzyme activity of at least 90% with respect to the initial activity after about 20 hours at pH 7.0 and 20.degree. C. In addition a process is described for the production of the enzyme from Leuconostoc. The enzyme is preferably suitable for the determination of ATP or reaction partners which can be converted into 6-phosphogluconolactone.

Abstract: A method is provided, in one embodiment, for the determination of an analyte in a biological fluid sample in the presence of a substance interfering with an assay for the analyte. This embodiment is implemented by using antibodies to cause the selective immunoreaction of at least one of the analyte or the interfering substance and then conducting an assay for the analyte in at least one of the immunoreactants or the non-reactants. Another embodiment provides a disposable reaction device to implement the method. The invention is applicable to the detection of a wide variety of analytes, including cholesterol in a targeted lipoprotein class in the presence of cholesterol in another class; to targeted isozymes of enzymes such as creatine kinase, lactate dehydrogenase, amylase, and alkaline or acid phosphatases in the presence of other isozymes; as well as to targeted immunoglobulins in the presence of non-targeted immunoglobulins.

Abstract: The present invention is directed to a membrane-based immunoassay method for an analyte of interest having at least two sterically separate antigenic sites. The method comprises providing a reactive membrane having a calibration zone and a test zone, wherein the calibration zone is characterized by having a predetermined amount of the analyte of interest immobilized via a first antibody as a first specific binding pair to a solid phase, the immobilized first binding pair being covalently cross-linked such that any remaining binding sites on said first immobilized antibody are substantially incapable of further specifically binding to any additional analyte, but at least some of said analyte is capable of specifically binding to a preselected amount of a labelled second antibody.

Abstract: Methods and reagents for determining the lapse of time since an acute disease event, such as the occurrence of a myocardial infarction, are presented. A serum or plasma sample is assayed to determine the concentration of two different analytes selected from a group of creatine kinase-MB species. From these measurements, the time of the acute event can be more accurately determined. Novel antibodies, labeled and insolubilized derivatives of these antibodies, labeled proteins, and kits containing one or more of these reagents are also described.

Abstract: Methods and reagents for determining the lapse of time since an acute disease event, such as the occurrence of a myocardial infarction, are presented. A serum or plasma sample is assayed to determine the concentration of two different analytes selected from the group consisting of creatine kinase-MB species and creatine kinase-BB species. From these measurements, the time of the acute event can be more accurately determined. Novel antibodies, labeled and insolubilized derivatives of these antibodies, labeled proteins, and kits containing one or more of these reagents are also described.

Abstract: The present invention discloses a rapid assay method for quantitatively determining the complete isoenzyme profile of a biological fluid and a multiple-assay reagent system for carrying out the method. In one preferred embodiment, a multiple-assay reagent system is disclosed for quantifying the complete isoenzyme profile of lactate dehydrogenase in blood serum, based on two measured parameters and three performed assays.

Abstract: A formulation for stabilizing enzymatic activity and immunoreactivity of creatine kinase and creatine kinase isoenzymes comprising animal serum, creatine kinase and/or creatine kinase isoenzymes, an effective amount of a buffer having a pKa in the range of 6.2-7.6 to maintain pH of the formulation at 6.7.+-.0.1, an effective amount of a non-thiol antioxidant to prevent oxidation of creatine kinase or creatine kinase isoenzyme thiol groups, an effective amount of a non-reducing polyol to stabilize immunoreactivity of creatine kinase or creatine kinase isoenzymes, and an effective amount of an antimicrobial to prevent microbial growth is provided.

Abstract: An integral multilayer analytical element for the determination of ammonia or an ammonia-producing substance comprising a light-transmissive liquid-impermeable support, an indicator layer containing an indicator which produces a detectable change by gaseous ammonia, a liquid permeation barrier layer, a reagent layer containing an alkaline buffer and optionally a reagent capable of reacting with a substance to produce ammonia and a spreading layer laminated in this order, which is improved by that the indicator layer contains a polyvinyl alkyl ether, and/or which is improved by that the surface of said support facing toward the indicator layer is undercoated with a polyvinyl alkyl ether, a hydroxyalkyl cellulose, an alkyl cellulose, polystyrene, a polyalkyl methacrylate, polyviriylidene chloride, polyvinyl alcohol or polyvinyl pyrrolidone, substantially not containing ammonia and ammonium ion.

Abstract: Diarylimidazoles of the general formula: ##STR1## wherein R.sup.1 is a radical of the general formula: ##STR2## in which R.sup.3 and R.sup.6 are hydrogen atoms, R.sup.4 and R.sup.5, which can be the same or different, are lower alkyl radicals or R.sup.3 /R.sup.4 and /or R.sup.5 /R.sup.6 in each case together represent a lower alkylene radical and R.sup.2 is a lower alkyl radical, and/or of a salt thereof, are useful as redox indicators, particularly in the presence of a SH group-containing substance.

Abstract: A method for detecting ischemic states in a patient by contacting a sample of serum, plasma, fluid or tissue with a metal ion capable of binding to metal ion binding sites in the sample to form a mixture, and then detecting the presence of unbound metal ions to determine the occurrence of ischemia.

Abstract: Methods and reagents for determining the lapse of time since an acute disease event, such as the occurrence of a myocardial infarction, are presented. A serum sample is assayed to determine the concentration of two analyte sets. From these measurements, the time of the acute event can be more accurately determined. Novel antibodies, labeled and insolubilized derivatives of these antibodies, labeled proteins, and kits containing one or more of these reagents are also described.

Abstract: Diarylimidazoles of the general formula: ##STR1## wherein R.sup.1 is a radical of the general formula: ##STR2## in which R.sup.3 and R.sup.6 are hydrogen atoms, R.sup.4 and R.sup.5, which can be the same or different, are lower alkyl radicals or R.sup.3 /R.sup.4 and/or R.sup.5 /R.sup.6 in each case together represent a lower alkylene radical and R.sup.2 is a lower alkyl radical, and/or of a salt thereof, are used as redox indicators in the colorimetric diarylimidazoles are not influenced by the presence of a SH group-containing substance. The peroxidate-acting substance can be used to determine the presence of creatine kinase.

Abstract: A stabilizer for maintaining a constant level of CO.sub.2 in coenzyme containing enzymatic CO.sub.2 diagnostic reagents is disclosed, comprising rate-limiting amounts of (a) the diagnostic reagents and (b) coenzyme-regenerating reagents, e.g., wherein (a) is malate dehydrogenase, phosphoenolpyruvate carboxylase and NADH, and (b) is glucose dehydrogenase and glucose, as are methods of use and kits containing a diagnostic reagent and stabilizer.

Abstract: Single or multi-cell reservoir sensors with single illumination sources and one or more detectors per cell unit have an arrangement whereby a gaseous, vapor or liquid sample enters the cell body and interacts with a sensing solution to detect and quantify a given species. Entrance of the sample into the sensor is through an opening in the cell body which may be covered with a membrane to contain the sensing reagent and to presort the species entering the cell. Reservoir cells can be used with organic, inorganic or biochemical sensing materials. A variety of sensors as alcohol, drugs of abuse, organic halides, cyanide and inorganic ions are provided.

Abstract: A stable dry multi-layer analytical element for enzyme or triglyceride analysis in a fluid sample is prepared containing first and second layers on a support. The first layer contains a tetrazolium salt as a dye forming precursor. The second layer is adjacent the first layer and contains an electron-transmitting agent. Either layer contains a co-enzyme in oxidized form and either layer contains a reagent containing an enzyme substrate, enzyme or co-enzyme other than the oxidized co-enzyme. The analytical element has improved storage stability and low fog density before and after storage.

Abstract: Dry transparent analytical elements can be used to determine analytes which have been separated by electrically induced migration through a solid medium, e.g. by electrophoresis, or which are intracellular enzymes. The dry transparent element is placed on a plate containing the analytes, and kept there until the analytes have reacted to produce a non-diffusible detectable species solely in the element. The element is removed and the detectable species is evaluated therein. The elements contain a water-insoluble binder material having an interactive composition dispersed therein which reacts with analyte to produce the non-diffusible species. The same electrophoretic plate can be used to successively determine the same or a plurality of analytes since it is not altered or destroyed by contact with the dry element.

Abstract: A two site cross-reaction immunometric sandwich assay method for the detection and measurement of an analyte, such as creatine phospho-kinase-MB, in serum comprising the selection of two different antibodies each of which is specific to a different analyte but each of which will cross-react with the analyte of interest. The first antibody is reacted with the unknown sample utilizing a solid-phase to bind the first antibody. Separation of the solid and liquid portions of the first reaction is accomplished and the solid portion thereof is reacted with the second antibody which is tagged. The solid portion and liquid portion of the second reaction are separated and the solid portion is tested for the tag as an indication of the presence of said analyte. With particular reference to testiong for creatine phospho-kinase-MB in human serum, the cross-reacting antibodies utilized are antibody to creatine phospho-kinase-BB and creatine phospho-kinase-MM.

Abstract: A completely water-soluble, solid, labile biochemical-containing diagnostic reagent is prepared without the need of a lyophilization step, by spraying, preferably by a fluidized bed process, an aqueous solution of labile biochemical, e.g., an enzyme, onto small particles, e.g., lower than 20 mesh, of an inert, completely water-soluble solid bulking agent, e.g., mannitol; drying the resultant labile biochemical-coated bulking agent to the desired dryness; and then forming resultant dried labile biochemical-coated bulking agent into a tablet suitable for a diagnostic test reagent, said tablet having a predetermined rate of dissolution.

Abstract: A two site cross-reaction immunometric sandwich assay method for the detection and measurement of an analyte, such as creatine phospho-kinase-MB, in serum comprising the selection of two different antibodies each of which is specific to a different analyte but each of which will cross-react with the analyte of interest. The first antibody is reacted with the unknown sample utilizing a solid-phase to bind the first antibody. Separation of the solid and liquid portions of the first reaction is accomplished and the solid portion thereof is reacted with the second antibody which is tagged. The solid portion and liquid portion of the second reaction are separated and the solid portion is tested for the tag as an indication of the presence of said analyte. With particular reference to testing for creatine phospho-kinase-MB in human serum, the cross-reacting antibodies utilized are antibody to creatine phospho-kinase-BB and creatine phospho-kinase-MM.

Abstract: A stable human serum based control for the assay of Total LD and CK and their isoenzymes. This control may be lyophilized and reconstituted and still provide the same enzyme activity prior to lyophilization, for seven (7) days after reconstitution, if stored in the dark at or about 2.degree.0 to 8.degree. C. No thiol compounds other than the amount normally used to purify CK isoenzymes are found in this highly stable control.

Abstract: A blend of monoclonal antibodies is disclosed. The blend inhibits the activity of creatine kinase-MM at least 99.5 percent. The blend is useful in determining the level of creatine kinase-MB activity in biological fluids.

Abstract: A method for testing sperm quality comprising obtaining a sperm sample; detecting CK enzyme from the sperm sample; measuring a first CK enzyme concentration for CKX isoforms of the CK enzyme; and determining a sperm quality parameter based upon the first CK enzyme concentration. Preferably a second CK enzyme concentration is measured for CKB isoforms of the CK enzyme and is also used as a basis for determining the sperm quality parameter. Measurements of the levels of CKX and CKB isoforms by electrophoresis and fluorescence techniques are used to establish the first and second CK enzyme concentrations. The sperm quality parameter is proportional to the ratio of the CKX isoform level to the sum of the CKX and CKB isoform levels. Sperm which meets a predetermined minimum sperm quality level is selected for use in vivo or in vitro fertilization attempts on eggs.

Abstract: An analytical element for analyzing a specific component in a liquid sample, comprising a light-transmissive and liquid-impermeable support having thereon successively a first reagent layer and a second reagent layer, and a porous spreading layer provided above said second reagent layer, and containing an electron transport agent, a dye-forming precursor material, an oxidized type coenzyme, a buffering agent and at least one reagent capable of converting said oxidized type coenzyme to a reduced type coenzyme through a specific component in a liquid sample, wherein said oxidized type coenzyme is contained in said porous spreading layer, and a lactate dehydrogenase inhibitor is contained in at least one of said second reagent layer and said porous spreading layer.According to this invention, error originating from LDH and lactic acid present in a biological liquid sample can be eliminated and the accuracy of analysis can be improved.

Abstract: A novel NAD synthetase is produced by culturing a broth of Bacillus stearothermophilus H-804 FERM BP-1408. This new enzyme selectively catalyzes the reaction ##STR1## without catalyzing the reaction ##STR2## The enzyme uses ammonia or ammonium ion as a substrate, but does not use either glutamine or asparagine. Also disclosed is an assay method using the enzyme, for any one of ATP, deamide-NAD, ammonia or ammonium ion in a specimen to be assayed.

Abstract: A reagent for the determination of creatine kinase is comprised of a reagent group containing N-acetylcysteine and ethylenediaminetetraacetic acid and a reagent group containing magnesium, whereby the stability thereof is acheived.

Abstract: The present invention provides a test carrier (1) for the analytical determination of a component of a body fluid with a base layer (2) and at least two planar test layers which, in the initial state of the test carrier, before carrying out the determination, are separate from one another but can be brought into contact with one another by external manipulation, wherein a first test layer (8) and a second test layer (10) are arranged on the base layer essentially next to one another but separated in the initial state by a gap, a contact element (11, 17, 18, 20) being provided which consists of a capillary-active material which is so dimensioned that it can bridge the gap (12) and which is so mounted and arranged that, in a first position, it cannot contact at least one of the test layers (8, 10) but, by external pressure, it can be brought into a second position in which it contacts both test layers in such a manner that a liquid exchange between the test layers is possible.

Abstract: Certain phenols and anilines can be used as electron transfer agents to increase the rate of oxidation of leuco dyes by peroxidase. These phenols and anilines can react with hydrogen peroxide in the presence of peroxidase to provide intermediates which have higher oxidation potentials than the slowly oxidized substrates, e.g. the leuco dyes. These phenols and anilines can be used to advantage in both solution and dry assays of various analytes. They are particularly useful for the determination of an immunologically reactive ligand in an immunoassay.

Abstract: A completely water-soluble, solid, labile biochemical-containing diagnostic reagent is prepared without the need of a lyophilization step, by spraying, preferably by a fluidized bed process, an aqueous solution of labile biochemical, e.g., an enzyme, onto small particles, e.g., lower than 20 mesh, of an inert, completely water-soluble solid bulking agent, e.g., mannitol; drying the resultant labile biochemical-coated bulking agent to the desired dryness; and then forming resultant dried labile biochemical-coated bulking agent into a tablet suitable for a diagnostic test reagent, said tablet having a predetermined rate of dissolution.

Abstract: A multilayer analytical element for the determination of a clinically significant enzyme analyte comprises a photosensitive compound (e.g. a photosensitive dye or dye precursor) and a filter layer containing one or more filter dyes. The filter layer is situated in the element such that incident radiation used to detect a density change resulting from interaction of the analyte and the photosensitive compound passes through the filter layer before it reaches the photosensitive compound. The use of the filter layer inhibits premature changes in the photosensitive compound caused by incident radiation. This element is particularly useful for the determination of creatine kinase or one of its isoenzymes, e.g. creatine kinase-MB.

Abstract: An improved method and reagents are disclosed for determining a ligand in an assay solution containing the ligand, a reagent system and a luminescent compounds, wherein the intensity of the light emitted by the assay solution is related to the change in the transmittive properties of the assay solution produced by the interaction of the ligand to be determined and a reagent system capable of producing a change in the transmittive properties of the assay solution in the presence of the ligand.

Abstract: A reagent system for assaying creatine kinase is disclosed. The reagent system consisting essentially of a first reagent comprising glucose-6-phosphate dehydrogenase, .beta.-nicotinamideadenine dinucleotide (phosphate), and adenosine diphosphate, and a second reagent comprising creatine phosphate, said second reagent being maintained at a pH of from 7.5 to 10, and at least one of said first reagent and said second reagent containing glucokinase and glucose. The creatine kinase-assaying reagent exhibits remarkably improved stability in a dissolved state so that it can be prepared in large quantities and can be conventionally utilized to cope with urgent clinical examinations.

Abstract: RNA such as messenger RNA is digested to nucleotide phosphates including AMP or ADP. The ATP or a byproduct of the phosphorylation, e.g., pyruvate, is detected. Exemplary enzymes used (with appropriate co-reactants and co-factors) are: (1) polynucleotide phosphorylase, pyruvate kinase and luciferase, or (2) phosphodiesterase (or RNase), myokinase, pyruvate kinase and luciferase. The phosphorylation to ATP (e.g., with pyruvate kinase) is preferably coupled with the previous (reversible) enzymatic step.

Abstract: A multilayer analytical element for the determination of creatine kinase comprises a support having thereon, in order and in fluid contact, a registration layer and an isotropically porous spreading layer. The registration layer contains a binder material at a coverage of at least about 8 g/m.sup.2, which coverage improves the stability and keeping properties of the element in high humidity environments. This element is useful in an analytical method for determining total creatine kinase or any one of its isoenzymes, e.g. creatine kinase-MB.

Abstract: A method for preparing a blush polymer coating composition containing an immunologically reative species comprises milling the species and the other materials used in the composition to uniformly disperse the species therein. This coating composition can be used to prepare analytical elements for determining analytes (e.g. creating kinase-MB) whereby the effects of potential interferents are immunochemically removed. By milling the immunologically reactive species, e.g. antisera, into the coating composition, the resulting element has improved stability resulting in improved keeping in high humidity environments.

Abstract: A highly sensitive quantitative assay method for any one component which is L-glycero-3-phosphate (G3P), dihydroxyacetone-3-phosphate (DHAP), nicotinamide adenine dinucleotide (NAD) or reduced NAD, in a specimen to be assayed, comprising causing this component in the specimen to take part in the cycling reaction ##STR1## wherein GPO is glycerophosphate oxidase and GPDH is glycerophosphate dehydrogenase, and measuring a detectable change in the reaction system. There is thus provided a novel G3P-GHAP cycling reaction using GPO, which consumes O.sub.2 and generates H.sub.2 O.sub.2 and DHAP, with a substrate of G3P, and furthermore GPDH which consumes reduced NAD and generates NAD and G3P, with a substrate of DHAP. Examples of specimens are specimens which contain any one of G3P, DHAP, NAD or reduced NAD, or which liberate or generate such a component.

Abstract: Compounds useful in a simultaneous multiple assay for analytes such as steroids, proteins, peptides, carbohydrates or drugs. The compound or compounds are prepared by labelling an individual analyte with a radioisotope through a chelating agent to form a coordinated compound. The assay uses one or more chelated labelled analytes with one or more labelled analytes wherein each radioisotope is different.

Abstract: There is provided an assay method for determining the concentration of magnesium ions in biological fluids. The method comprises the introduction of a sample of biological fluid to a magnesium-free assay solution containing at least one reactant and an enzyme capable of catalyzing a reaction with at least one reactant wherein the enzyme activity, and hence the rate of reaction, is partially or totally dependent on and correlatable to the concentration of magnesium that is present. The rate of reaction is measured by monitoring the loss of a detectable reactant or the formation of a detectable product.

Abstract: A method is disclosed for preparing a soluble stable enzyme. The method comprises the steps of reacting in a liquid media an enzyme with a polymer having pendant groups capable of covalently bonding with pendant groups on the enzyme. The enzyme and polymer are mixed with at least one composition which affects the activity of the enzyme. Such a composition can be selected from the enzyme substrate, product of the enzyme substrate reaction, an activator for the enzyme and/or inhibitor for the enzyme. In addition, a composition can be added which can also competitively react with the available pendant groups of the polymer.

Abstract: A process for conducting fast, rapid two site, two step immunoradiometric tests for CK-MB.In a first series of steps, a mobile particulate solid-phase having an isoenzyme selected from the group of CK-BB and CK-MM immobilying bound on its surface is suspended in a matrix of pooled match human serum. The mixture is incubated, diluted, and centrifuged.In a second series of steps, the resulting solid is incubated with a radio labeled antibody that is specific to the isoenzyme not used in the first series of steps. Counting the radioactivity gives the amount of CK-MB in the patients serum.

Abstract: The invention relates to a method and novel reagents for detecting a ligand in a biological sample. In the method, the sample is combined with (i) an enzyme or an enzyme bound to a first macromolecular compound, (ii) substrate for the enzyme, and (iii) an antibody complex comprising anti-ligand bound to anti-enzyme and a second macromolecular compound bound to either one or both of the anti-ligand and anti-enzyme. The activity of the enzyme varies as a function of the unknown amount of ligand contained in the biological sample.

Abstract: In a dry analytical element for the determination of creatine kinase enzymatic activity is disclosed, comprising at least one porous medium and at least one water permeable layer having a liquid contact relation with the porous medium, the porous medium or the water permeable layer contains creatine phosphoric acid, ADP, a thiol compound as a creatine kinase activation agent, glucose, hexokinase, G6PDH, NAD.sup.+, an electron transmission agent and a formazane dye forming tetrazolium salt, the improvement wherein at least one water permeable layer having a liquid contact relation with the porous medium contains a formazane dye forming tetrazolium salt and not more than 16 g/m.sup.2 of gelatin.