Confirmation of a ping-pong mechanism for S-adenosyl-L-methionine:magnesium protoporphyrin methyltransferase of etiolated wheat by an exchange reaction.
An exchange reaction between unlabeled S-adenosyl-L-methionine and radiolabeled S-adenosyl-L-homocysteine has been used to confirm the occurrence of a ping-pong mechanism in S-adenosyl-L-methionine:magnesium protoporphyrin methyltransferase of etiolated wheat. The enzyme, S-adenosyl-L-homocysteine hydrolase, has been used to prepare radiolabeled S-adenosyl-L-homocysteine from labeled adenosine and DL-homocysteine. The exchange reaction was accomplished with a methyltransferase preparation purified by affinity chromatography on hemin-linked Sepharose 4B, and radioactivity was exchanged into unlabeled S-adenosyl-L-methionine to an extent of 70% of the theoretical maximum value.
Yee
W C
WC
Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
Eglsaer
S J
SJ
Richards
W R
WR
D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D007700:Kinetics; D008780:Methyltransferases / Q000302:isolation & purification*; D010105:Oxygenases; D012435:S-Adenosylhomocysteine / Q000138:chemical synthesis; D012436:S-Adenosylmethionine; D014908:Triticum / Q000201:enzymology*
D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine; D010105:Oxygenases; C053161:magnesium protoporphyrin monomethyl ester oxidative cyclase; D008780:Methyltransferases; C060234:magnesium-protoporphyrin methyltransferase