Suggested Reaction 1.14.16.-

Left

L-Methionine S-oxide
+6,7-Dihydrobiopterin
+H2O

Right

L-Methionine
+2-Amino-6-(1,2-dihydroxypropyl)-5,6,7,8-tetrahydoro-4(1H)- pteridinone
+O2

[BiSSCat | GREP ]