1.21.98.3	131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine = 131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + 5'-deoxyadenosine + L-methionine	(1b)	
1.21.98.3	131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine = 3,8-divinyl protochlorophyllide a + 5'-deoxyadenosine + L-methionine	(1c)	
1.21.98.3	magnesium-protoporphyrin IX 13-monomethyl ester + 3 S-adenosyl-L-methionine + H2O = 3,8-divinyl protochlorophyllide a + 3 5'-deoxyadenosine + 3 L-methionine	overall reaction	
1.21.98.3	magnesium-protoporphyrin IX 13-monomethyl ester + 3 S-adenosyl-L-methionine + H2O = 3,8-divinyl protochlorophyllide a + 3 5'-deoxyadenosine + 3 L-methionine	the oxygen-independent conversion of Mg-protoporphyrin IX monomethyl ester (Mg-PME) to protochlorophyllide (Pchlide) is catalyzed by the anaerobic Mg-PME cyclase termed BchE, via an unusual radical S-adenosylmethionine (SAM) and cobalamin-dependent BchE catalysis	
1.21.98.3	magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine + H2O = 131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + 5'-deoxyadenosine + L-methionine	(1a)