OXIDOREDUCTASE, NITRITE REDUCTASE, HIGH-THROUGHPUT SCREENING, OXIDASE, COPPER, FAD, FLAVOPROTEIN, METAL-BINDING, NITRATE ASSIMILATION, PERIPLASM, PYRROLIDONE CARBOXYLIC ACID MET150LEU/PHE312CYS VARIANT OF NITRITE REDUCTASE FROM ALCALIGENES FAECALIS 3H56