Redox status affects the catalytic activity of glutamyl-tRNA synthetase

► Activity of glutamyl-tRNA synthetase is lost by oxidation with H2O2 and hemin. ► Cysteines from a Zn2+ binding site are the targets of oxidation. ► Zn2+ is released by oxidation, but activity is lost before Zn2+ is released. ► ATP and tRNA protect the cysteines from oxidation. ► Redox status of GluRS1 might regulate protein and tetrapyrrole biosynthesis.