ID 4.4.1.36 DE hercynylcysteine S-oxide lyase. CA S-(hercyn-2-yl)-L-cysteine S-oxide + AH2 + H(+) = ergothioneine + CA pyruvate + A + NH4(+). CC -!- The enzyme, characterized from the bacterium Mycobacterium smegmatis, CC cayalyzes the last step in the pathway of ergothioneine biosynthesis. CC -!- The enzyme forms a 2-sulfenohercynine intermediate, which is reduced CC to ergothioneine non-enzymically by a thiol. CC -!- In vitro, DTT can serve this function. //