The biochemical pathway that makes BH4 requires GTP as the substrate and three dedicated enzymes (GTP cyclohydrolase I, 6pyruvoyltetrahydropterin synthase, and sepiapterin reductase); the key redox cofactors used in the pathway and Structure of Human Glutathione Reductase (PDB ID: 3DK9) (a) Surface Download Scientific Diagram How to assess Vitamin B2 Status? B2 nutritional status is assessed through the ERYTHROCYTE GLUTATHIONE REDUCTASE ACTIVITY COEFFICIENT (EGRAC), which should be < 1.2. What is this coefficient? FAD Pedro Carrera Bastos Item Scheme showing the enzymatic reactions that catalyze the pyruvate dehydrogenase complex, including pyruvate dehydrogenase activity and diaphorase activity of DLD (A) as well as the glutathione reductase peroxidase activity (B).