Methyl-Cbl, methyl- cobalamin; SAH,
S-adenosyl-L-homocysteine; X, methyl acceptor; C[H.sub.3]-X, methylated product; Pi, phosphate; PPi, pyrophosphate.
The presence of caffeic acid or chlorogenic acid inhibited DNA methylation predominantly through a non-competitive mechanism, and this inhibition was largely due to the increased formation of
S-adenosyl-L-homocysteine (SAH, a potent inhibitor of DNA methylation), resulting from the catechol-O-methyltransferase (COMT)-mediated O-methylation of these dietary catechols.
After donation of the activated methyl group to an acceptor, AdoMet is converted into total Hcy by formation of
S-adenosyl-L-homocysteine (AdoHcy) (10).
Synthesis and antiviral activity of some new
S-adenosyl-L-homocysteine derivatives.
D,L-Homocysteine and S-adenosyl-l-homocysteine hydrolase from rabbit erythrocytes were obtained from Sigma, and Tris base was obtained from Sigma-Aldrich.
The enzymatic synthesis of S-adenosyl-L-homocysteine from adenosine and homocysteine.
Both methods are based on enzymatic conversion of homocysteine to
S-adenosyl-L-homocysteine, which is subsequently detected by a competitive immunoassay.
This assay involves the initial reduction of Hcy, mixed-disulfide, and protein-bound Hcy to free Hcy with dithiothreitol, followed by conversion to
S-adenosyl-L-homocysteine (SAH) by bovine SAH hydrolase and excess adenosine.
Both assays are based on enzymatic conversion of Hcy to
S-adenosyl-L-homocysteine (SAH) by the action of SAH hydrolase (SAHase; EC 3.3.1.1), followed by quantification of SAH in a competitive immunoassay with the use of a monoclonal anti-SAH antibody.
The "Abbott Homocysteine (HCY) assay" is a fluorescence polarization immunoassay based on the highly selective enzymatic conversion of homocysteine to
S-adenosyl-L-homocysteine, which is then recognized by a monoclonal antibody (2).
This assay is based on enzymatic conversion of tHcy (after reduction and release of endogenous homocysteine from proteins and/or disulfides) to
S-adenosyl-L-homocysteine (SAH) by the action of SAH hydrolase (EC 3.3.1.1), followed by quantification of SAH in a competitive immunoassay with use of a monoclonal antibody against SAH.
The method is based on enzymatic conversion of Hcy to
S-adenosyl-L-homocysteine (SAH) by the action of SAH hydrolase (SAHase; EC 3.3.1.1), followed by quantification of SAH in a competitive immunoassay with use of a monoclonal anti-SAH antibody [5].