Purification and some properties of cobalamin-dependent methionine synthase from rat liver.
Cobalamin-dependent methionine synthase was purified from rat liver. The enzyme activity was separated into two peaks upon Mono-Q column chromatography. Peaks I and II of the enzyme, eluted in this order, were purified 18,000- and 44,000-fold in overall yields of 0.7 and 1.8%, respectively. Peak II methionine synthase, the major fraction, was homogeneous as judged by SDS-polyacrylamide gel electrophoresis. The enzyme was a large monomeric protein with an apparent molecular weight of 143,000 Da. Interconversion of the enzyme between the two peaks was not observed during purification procedures. The enzyme required S-adenosylmethionine and a reducing system for activity. Apparent K(m) values of the peak II enzyme for 5-methyltetrahydrofolate and homocysteine were 75 and 1.7 microM, respectively.
Yamada
K
K
Faculty of Engineering, Okayama University, Japan.
Tobimatsu
T
T
Kawata
T
T
Wada
M
M
Maekawa
A
A
Toraya
T
T
D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000302:isolation & purification* / Q000378:metabolism*; D000818:Animals; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D051381:Rats; D012436:S-Adenosylmethionine / Q000378:metabolism; D014805:Vitamin B 12 / Q000378:metabolism*
D012436:S-Adenosylmethionine; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D014805:Vitamin B 12