Squalene methyltransferase explained

Squalene methyltransferase
Ec Number:	2.1.1.262

Squalene methyltransferase (TMT-1, TMT-2) is an enzyme with systematic name S-adenosyl-L-methionine:squalene C-methyltransferase.^[1] This enzyme catalyses the following chemical reaction

\rightleftharpoons 2 S-adenosyl-L-homocysteine + 3,22-dimethyl-1,2,23,24-tetradehydro-2,3,22,23-tetrahydrosqualene (overall reaction)

(1a) S-adenosyl-L-methionine + squalene

\rightleftharpoons S-adenosyl-L-homocysteine + 3-methyl-1,2-didehydro-2,3-dihydrosqualene

(1b) S-adenosyl-L-methionine + 3-methyl-1,2-didehydro-2,3-dihydrosqualene

\rightleftharpoons S-adenosyl-L-homocysteine + 3,22-dimethyl-1,2,23,24-tetradehydro-2,3,22,23-tetrahydrosqualene

There are two isoforms in the green alga Botryococcus braunii BOT22 that differ in their specificity .

Notes and References

1. Niehaus TD, Kinison S, Okada S, Yeo YS, Bell SA, Cui P, Devarenne TP, Chappell J . Functional identification of triterpene methyltransferases from Botryococcus braunii race B . The Journal of Biological Chemistry . 287 . 11 . 8163–73 . March 2012 . 22241476 . 3318757 . 10.1074/jbc.m111.316059 . free .