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. Author manuscript; available in PMC: 2013 Dec 1.
Published in final edited form as: Free Radic Biol Med. 2012 Sep 26;53(11):2178–2187. doi: 10.1016/j.freeradbiomed.2012.09.028

Figure 4. The flow of metabolites through one-carbon metabolism is influenced by redox.

Figure 4

The oxidation of key enzymes (shown in grey bubbles) limits their activity, and stops the flow of metabolites through the methionine cycle. SAM synthetase (MAT) can become inactivated through reversible oxidation. Oxidation of the Cbl core of Methionine synthase (MS) leads to its inactivation, however Methionine synthase reductase (MTRR) can use SAM as a cofactor to restart the enzyme. At the same time, an oxidizing environment can increase the activity of enzymes such Cystathionine β-synthase (CBS) to siphon sulfur into the production of glutathione.