ID 1.14.99.52 DE L-cysteinyl-L-histidinylsulfoxide synthase. CA L-cysteine + L-histidine + O2 = H2O + L-alanin-3-yl L-histidin-5-yl CA sulfoxide. CC -!- The enzyme participates in ovothiol biosynthesis. CC -!- It also has some activity as EC 1.13.11.20, and can perform the CC reaction of EC 1.14.99.50. //