Squalene methyltransferase

Squalene methyltransferase (EC 2.1.1.262, TMT-1, TMT-2) is an enzyme with systematic name S-adenosyl-L-methionine:squalene C-methyltransferase. 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 .

References

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

Transferase: one carbon transferases (EC 2.1)

N-	Histamine N-methyltransferase Phenylethanolamine N-methyltransferase Amine N-methyltransferase Phosphatidylethanolamine N-methyltransferase
O-	5-hydroxyindole-O-methyltransferase/Acetylserotonin O-methyltransferase Catechol-O-methyl transferase
Homocysteine	Betaine-homocysteine methyltransferase Homocysteine methyltransferase Methionine synthase
Other	Phosphatidyl ethanolamine methyltransferase DNMT3B Histone methyltransferase Thymidylate synthase DNA methyltransferase Thiopurine methyltransferase Cyclopropane-fatty-acyl-phospholipid synthase

Hydroxymethyltransferase	Serine hydroxymethyltransferase 3-methyl-2-oxobutanoate hydroxymethyltransferase
Formyltransferase	Phosphoribosylglycinamide formyltransferase Inosine monophosphate synthase
Other	Glutamate formimidoyltransferase Aminomethyltransferase

Carboxy	methylmalonyl-CoA carboxytransferase
Carbamoyl	Aspartate carbamoyltransferase Ornithine carbamoyltransferase Oxamate carbamoyltransferase Putrescine carbamoyltransferase 3-hydroxymethylcephem carbamoyltransferase Lysine carbamoyltransferase N-acetylornithine carbamoyltransferase

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)