The Archaean nrdJ gene encodes a “Class II” type of one of these enzymes that uses deoxy·adenosyl·cobalamin to activate a cysteine residue. In the presence of one of its four regulatory molecules, one of these enzymes clamps down its ten-stranded beta/alpha barrel to bring together the active and specificity sites. ADA deficiency inhibits DNA synthesis since a buildup of dATP inhibits one of these enzymes that uses two ferric iron atoms to generate a stable tyrosyl (tie-roh-SEEL) free radical. One of these enzymes uses (*) NADPH to convert gluta·thione from its inactive di·sulfide form to its active sulf·hydryl form. Enzymes of this type convert (-5[1])di·hydro·folate to tetra·hydro·folate, convert ribo·nucleotides to (10[1])de·oxy·ribo·nucleotides, and convert HMG-CoA to a cholesterol precursor. For 10 points, what kind of enzyme adds electrons to its substrate? (10[2])■END■