Compositions – Chemiluminescent
Reexamination Certificate
2000-04-26
2001-10-02
Aulakh, Charanjit S. (Department: 1625)
Compositions
Chemiluminescent
C546S023000, C546S102000, C546S104000
Reexamination Certificate
active
06296787
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to chemiluminescent compounds which react with phosphatase enzymes to generate light. In particular, the present invention relates to chemiluminescent compounds containing a heterocyclic ring group and an enol phosphate group which react with oxygen upon removal of a phosphate group with a phosphatase enzyme to produce an enolate which reacts with to produce chemiluminescence and a carbonyl compound.
The present invention further relates to compositions for generating chemiluminescence by reaction with a phosphatase enzyme. Chemiluminescent compositions comprise a first compound containing a heterocyclic ring group and an enol phosphate group and a second compound which acts to increase light production from the reaction of the phosphate compound with a phosphatase enzyme. The present invention relates to methods for generating light or chemiluminescence by the reaction of a phosphatase enzyme with a chemiluminescent composition. In particular, the present invention relates to improvements in such methods which substantially increase light emission.
The invention further relates to the use of the chemiluminescent reactions and compositions in assay methods for detecting phosphatase enzymes and for detecting phosphatase-labeled specific binding partners in immunoassays, nucleic acid probe assays and the like.
The present invention relates to a process for the preparation of chemiluminescent compounds which react with phosphatase enzymes to generate chemiluminescence. The present invention relates to novel intermediates useful in this process. In particular, the present invention relates to a process and intermediates for preparing chemiluminescent compounds containing a heterocyclic ring group and an enol phosphate group which react with oxygen upon removal of a phosphate protecting group to produce chemiluminescence and a carbonyl compound.
BACKGROUND OF THE INVENTION
a. Chemiluminescent Detection of Phosphatase Enzymes.
Hydrolytic enzymes such as alkaline phosphatase are frequently used as markers or labels in enzyme-linked assays for biological molecules and other analytes of interest such as drugs, hormones, steroids and cancer markers. In addition, phosphatase enzymes, e.g. alkaline phosphatase (AP) and acid phosphatase (AcP), are clinically significant in their own right in human and veterinary diagnostics. Chemiluminescent detection of these enzymes offers a safe, convenient and sensitive means to provide a quantitative measure of the amount of enzyme in a sample or of the amount of an enzyme-labeled analyte or labeled specific binding partner for an analyte. Numerous chemiluminescent reaction schemes have been developed to quantitate the level of particular hydrolytic enzymes. Most of these schemes are complex and expensive, requiring multiple enzymes or several reagents. Commercial acceptance of most of such methods for large volume testing has been slow.
Applicant's co-pending U.S. patent application Ser. No. 08/585,090 which is fully incorporated herein by reference, discloses the chemiluminescent reaction of certain heterocyclic compounds bearing an enol phosphate group with a phosphatase enzyme. Light emission is enhanced in the presence of cationic surfactants allowing the phosphatase to be detected at levels of 10
−18
to 10
−19
mol.
Applicant's co-pending U.S. patent application Ser. No. 08/683,927 which is fully incorporated herein by reference, discloses the use of cationic aromatic compounds (CAC's) in conjunction with the chemiluminescent reaction of certain heterocyclic compounds bearing an enol phosphate group with a phosphatase enzyme to substantially increase the amount of light emitted. The detection limit of phosphatase enzymes is thereby dramatically lowered.
b. Chemically and Enzymatically Triagerable Dioxetanes.
Stable 1,2-dioxetanes bearing a protected phenol group triggering group undergo a chemiluminescent decomposition upon removal of a protecting group (A. P. Schaap, T. S. Chen, R. S. Handley, R. DeSilva, and B. P. Giri,
Tetrahedron Lett
., 1155 (1987); A. P. Schaap, R. S. Handley, and B. P. Giri,
Tetrahedron Lett
., 935 (1987); A. P. Schaap, M. D. Sandison, and R. S. Handley,
Tetrahedron Lett
., 1159 (1987); and A. P. Schaap,
Photochem. Photobiol
., 47S, 50S (1988)). Enzymatically triggerable dioxetanes bear an aryloxide substituent which is blocked by an enzymatically removable protecting group. Reaction with a hydrolytic enzyme in an aqueous buffer reveals an aryloxide anion which accelerates the chemiluminescent decomposition rate of the dioxetane by orders of magnitude. Chemically triggerable dioxetanes bear an aryloxide substituent which is blocked by a protecting group which is removed by a simple chemical agent. An example is deprotection of an acetoxy dioxetane with hydroxide or a silyloxy dioxetane with fluoride. Numerous examples of such triggerable dioxetanes are disclosed, for example, in U.S. Pat. Nos. 4,857,652, 5,068,339, 4,952,707, 5,112,960, 5,220,005, 5,326,882 and in PCT applications WO96/24849, WO94/10258 and WO94/26726. However, an inherent disadvantage of some triggerable dioxetanes is their tendency to generate background chemiluminescence in the absence of enzyme through slow thermal decomposition or non-enzymatic hydrolysis.
c. Luminol Derivatives.
A phosphate and a NAG derivative of luminol are known (K. Sasamoto, Y. Ohkura, Chem. Pharm. Bull., 38, 1323-5 (1991); M. Nakazono, H. Nohta, K. Sasamoto, Y. Ohkura, Anal. Sci., 8, 779-83 (1992)). Treatment of the luminol derivative with the appropriate enzyme liberates luminol which is reacted in a subsequent step with ferricyanide to produce light.
d. Luciferin Derivatives.
Phosphate and galactoside derivatives of firefly luciferin are known (N. Ugarova, Y. Vosny, G. Kutuzova, I. Dementieva, Biolum. and Chemilum. New Perspectives, P. Stanley and L. J. Kricka, eds., Wiley, Chichester, 511-4 (1981); W. Miska, R. Geiger, J. Biolumin. Chemilumin., 4, 119-28 (1989)). Treatment of the firefly luciferin derivative with the appropriate enzyme liberates firefly luciferin which is reacted in a second step with luciferase and ATP to produce light.
e. Reactions Involving the Generation of Reducing Agents.
Chemiluminescent methods involving the generation of a reducing agent from a phosphate ester catalyzed by alkaline phosphatase have been reported. (M. Maeda, A. Tsuji, K. H. Yang, S. Kamada, Biolum. and Chemilum. Current Status, 119-22 (1991); M. Kitamura, M. Maeda, A. Tsuji, J. Biolumin. Chemilumin., 10, 1-7 (1995); H. Sasamoto, M. Maeda, A. Tsuji, Anal. Chim. Acta, 306, 161-6 (1995)). The reducing agent causes a reaction between oxygen and lucigenin to produce light arising from the lucigenin. Representative reducing agents include ascorbic acid, glycerol, NADH, dihydroxyacetone, cortisol and phenacyl alcohol. These methods are distinguished from the present invention which involves the production of light from the deprotected fluorescent compound, not from lucigenin. The known methods of enzymatically generating a reducing agent for reaction with lucigenin all require a separate preliminary incubation step between the enzyme and the phosphate compound. This adds additional complexity and assay time.
U.S. Pat. No. 5,589,328 to Mahant discloses a chemiluminescent reaction whereby indoxyl esters, thioindoxyl esters and benzofuran esters are hydrolyzed by an enzyme and thereby generate superoxide. Luminescence is amplified by adding a chemiluminescence generating reagent such as lucigenin. Lucigenin produces chemiluminescence by reaction with superoxide.
f. Coupled Enzyme Methods.
Numerous other chemiluminescent methods and assays for determining hydrolytic enzymes such as phosphatase enzymes through coupled enzyme reactions are known. A compilation of such methods is listed in A. Tsuji, M. Maeda, H. Arakawa, Anal. Sci., 5, 497-506 (1989). Other examples of dual enzyme chemiluminescent reactions are described in U.S. Pat. No. 5,306,621 and commonly assigned application Ser. No. 08/300,367. The former
Akhavan-Tafti Hashem
Arghavani Zahra
DeSilva Renuka
Aulakh Charanjit S.
Handley Richard S.
Lumigen Inc.
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