Anti-S-Adenosyl-Homocysteine polyclonal antibody

The vaccinia virus mRNA capping enzyme is a multifunctional heterodimeric protein associated with the viral polymerase that both catalyses the three steps of mRNA capping and regulates gene transcription. The structure of a subcomplex comprising the C- terminal N7- methyl- transferase ( MT) domain of the large D1 subunit, the stimulatory D12 subunit and bound S- adenosyl- homocysteine ( AdoHcy) has been determined at 2.7A resolution and reveals several novel features of the poxvirus capping enzyme. The structure shows for the first time the critical role played by the proteolytically sensitive N- terminus of the MT domain in binding the methyl donor and in catalysis. In addition, the poxvirus enzyme has a completely unique mode of binding of the adenosine moiety of AdoHcy, a feature that could be exploited for design of specific anti- poxviral compounds. The structure of the poxvirus- specific D12 subunit suggests that it was originally an RNA cap 2 ' O- MT that has evolved to a catalytically inactive form that has been retained for D1 stabilisation and MT activity enhancement through an allosteric mechanism.

The study developed a novel quantitative detection method of homocysteine (Hcy), an independent risk factor for cardiovascular disease, based on an immunofluorescent test strip. The fluorescent nanospheres (F-NSs) were prepared by embedding fluorophores (Cy5) into poly(styrene-acrylate) copolymer nanospheres, then conjugated with streptavidin (SA) to obtain SA/F-NSs as a signal amplification label stored in sample diluents. Biotin-antibody was fixed on the conjugate pad to specifically capture S-adenosyl Hcy (SAH) in the sample, where SAH was transformed from S-adenosyl methionine (SAM) by Hcy S-methyltransferase catalysis using Hcy as a substrate, the formed SAH could be trapped by SA/F-NSs and biotin-antibody conjugates in a competitive way with SAH-bovine serum albumin fixed on the test line, a detection limit of 0.27 M Hcy was achieved. The fluorescence intensity of F-NSs remained stable during 273 days of storage, the bioactivity of the test strip was stable during 12 months of storage, and the strip possessed good reproducibility (intra-assay variability of 5.8%). Furthermore, other structural analogues SAM and cysteine showed negative results, validating the excellent specificity of the strips.