Selection of a mimotope peptide of S-adenosyl-L-homocysteine and its application in immunoassays.

A competitive immunoassay for S-adenosyl-L-homocysteine (SAH) has been used in the clinical test for homocysteine via an enzymatic conversion reaction. Since S-adenosyl-l-homocysteine is a relatively unstable compound, we have used peptide library phage display to select a new mimotope peptide that interacts with the anti-SAH antibody. By immobilizing the synthetic peptide on solid phase as a competitive surrogate for SAH, we demonstrate its utility in a competitive ELISA assay. The linear range of the assay for SAH was 0.4-6.4 µM, in good correlation to the conventional assay using an SAH-conjugated plate. Our results show that the mimotope peptide has potential to substitute for SAH in immunoassays.