Abstract: The invention provides bioconjugates of heterocylic compounds such as S-adenosylmethionine and S-adenosylhomocysteine with biotin or digoxigenin. The bioconjugates also include carbon and nitrogen linker moieties of varying length that are used to attach such compounds to biotin or digoxigenin. The conjugates are useful in immunoassays. The invention provides a method for detecting SAM and SAH, comprising the steps of: (a) preparing the following components: (i) bio-conjugates of SAM, SAM analogs or SAH; (ii) an europium, a terbium cryptate or other fluorophore as a donor that has a specific ligand for the tracer in the bio-conjugates of (i); (iii) an acceptor fluorescent dye that has the excitation spectra overlap those of donor's emissions and has an antibody specific for SAM or SAH labeled; (b) addition of the biological fluid containing said SAM or SAH; and (c) spectroscopic measurement of the fluorescence of the donor and the fluorescence of from the acceptor.

Abstract: The invention provides immunochromatographic test strips and methods for detecting and quantifying S-Adenosylmethionine (SAM), S-Adenosylhomocysteine (SAH) and Homocysteine (HCy) in a sample, comprising: (a) making fluorophore conjugated antibodies; (b) immobilizing SAM, SAH and HCy on a solid support; (c) providing a sample, combining said sample with a conjugate selected from the group consisting of lanthanide chelate conjugates and quantum dot conjugates (QD) with anti-SAM, anti-SAH or anti-HCy, wherein said combining is performed under conditions that allow formation of a competitive complex comprising said conjugate, said SAM, SAH or HCy on the solid support and SAM, SAH or HCy in a sample when present; and (d) detecting the presence of the complex, if present, by monitoring a spectral emission mediated by the fluorescent conjugates in the complex, wherein the emission indicates the presence and quantity of SAM, SAH or HCy in the sample.

Abstract: A method of detecting the presence or absence of a disease in a patient wherein said disease is accompanied by deficient levels of S-adenosylmethionine comprising: identifying a patient that is suspected of having said disease or is at risk of having said disease; obtaining a biological sample from said patient; determining the level of S-adenosylmethionine in said biological sample using an antibody derived from a hapten analog of S-adenosylmethionine; and correlating the level of S-adenosylmethionine in said biological sample with the presence or absence of said disease. The invention also provides methods for measuring SAH which is used to determine the methylation index (ratio of SAM/SAH) in biological fluids which is indicative of the health status of an individual.