S-Adenosyl methionine (SAM or SAMe) is an essential biomolecule involved in multiple biosynthesis and gene regulation processes. It is a substrate of enzymes for methylation of various biomolecules. The colorimetric SAM assay is based on measurement of light absorbance at 450 nm that is generated by  interaction of SAM with SAM dye. The assay can be used for measurements SAM concentrations in biochemical reactions or industrial products. It can also be used for activity assays of enzymes such as methyltransferases. The assay is compatible with common buffers such as 10 mM Tris-HCl, pH 7.5, 10 mM NaCl.  It is compatible with 1 mM EDTA, 0.5 % Triton, 10 % ethanol, phosphate at a concentration below 1 mM or DTT at a concentration below 0.1 mM.  It is not compatible with higher concentrations of phosphate or DTT. Samples with 100 µg/ml protein or DNA require an extended incubation time. High concentrations of proteins or DNA (> 100 µg /ml) should be avoided.

The Colorimetric S-Adenosyl Methionine (SAM) Assay Kit (Catalog Number SAM00) includes 500 µl of 10 x Buffer (0.1 M Tris-HCl, pH 7.5, 0.1 M NaCl, 2.5 ml of Reagent A and 500 µl of 10 x SAM dye.   It is for measurement of 100 samples using 96-well plates.  Cuvettes or 383-well plates may also be used for measurements.