Methyltransferases are a large group of enzymes that all methylate their substrates but can be split into several subclasses based on their structural features. The most common class of methyltransferases is class I, all of which contain a Rossmann fold for binding S-Adenosyl methionine (SAM). Class II methyltransferases contain a SET domain, which are exemplified by SET domain histone methyltransferases, and class III methyltransferases, which are membrane associated. Methyltransferases can also be grouped as different types utilizing different substrates in methyl transfer reactions. These types include protein methyltransferases, DNA/RNA methyltransferases, natural product methyltransferases, and non-SAM dependent methyltransferases. SAM is the classical methyl donor for methyltransferases, however, examples of other methyl donors are seen in nature. The general mechanism for methyl transfer is a SN2-like nucleophilic attack where the methionine sulfur serves as the leaving group and the methyl group attached to it acts as the electrophile that transfers the methyl group to the enzyme substrate. SAM is converted to S-Adenosyl homocysteine (SAH) during this process. The breaking of the SAM-methyl bond and the formation of the substrate-methyl bond happen nearly simultaneously. These enzymatic reactions are found in many pathways and are implicated in genetic diseases, cancer, and metabolic diseases. Another type of methyl transfer is the radical S-Adenosyl methionine (SAM) which is the methylation of unactivated carbon atoms in primary metabolites, proteins, lipids, and RNA.
In biochemistry, fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes called fatty acid synthases. This process takes place in the cytoplasm of the cell. Most of the acetyl-CoA which is converted into fatty acids is derived from carbohydrates via the glycolytic pathway. The glycolytic pathway also provides the glycerol with which three fatty acids can combine to form triglycerides, the final product of the lipogenic process. When only two fatty acids combine with glycerol and the third alcohol group is phosphorylated with a group such as phosphatidylcholine, a phospholipid is formed. Phospholipids form the bulk of the lipid bilayers that make up cell membranes and surrounds the organelles within the cells. In addition to cytosolic fatty acid synthesis, there is also mitochondrial fatty acid synthesis (mtFASII), in which malonyl-CoA is formed from malonic acid with the help of malonyl-CoA synthetase (ACSF3), which then becomes the final product octanoyl-ACP (C8) via further intermediate steps.
In enzymology, a 3'-demethylstaurosporine O-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a 7-methylxanthosine synthase is an enzyme that catalyzes the chemical reaction
In enzymology, a caffeate O-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a fatty-acid O-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a glycine N-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a methionine S-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a methylene-fatty-acyl-phospholipid synthase is an enzyme that catalyzes the chemical reaction
In enzymology, a phosphatidyl-N-methylethanolamine N-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a putrescine N-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a theobromine synthase is an enzyme that catalyzes the chemical reaction
In enzymology, a tRNA (adenine-N1-)-methyltransferase (EC 2.1.1.36) is an enzyme that catalyzes the chemical reaction
In enzymology, a tRNA (guanine-N1-)-methyltransferase (EC 2.1.1.31) is an enzyme that catalyzes the chemical reaction
In enzymology, a tRNA (guanine-N7-)-methyltransferase (EC 2.1.1.33) is an enzyme that catalyzes the chemical reaction
In enzymology, a tRNA (uracil-5-)-methyltransferase is an enzyme that catalyzes the chemical reaction
[Methionine synthase] reductase, or Methionine synthase reductase, encoded by the gene MTRR, is an enzyme that is responsible for the reduction of methionine synthase inside human body. This enzyme is crucial for maintaining the one carbon metabolism, specifically the folate cycle. The enzyme employs one coenzyme, flavoprotein.
Radical SAM enzymes belong to a superfamily of enzymes that use an iron-sulfur cluster (4Fe-4S) to reductively cleave S-adenosyl-L-methionine (SAM) to generate a radical, usually a 5′-deoxyadenosyl radical (5'-dAdo), as a critical intermediate. These enzymes utilize this radical intermediate to perform diverse transformations, often to functionalize unactivated C-H bonds. Radical SAM enzymes are involved in cofactor biosynthesis, enzyme activation, peptide modification, post-transcriptional and post-translational modifications, metalloprotein cluster formation, tRNA modification, lipid metabolism, biosynthesis of antibiotics and natural products etc. The vast majority of known radical SAM enzymes belong to the radical SAM superfamily, and have a cysteine-rich motif that matches or resembles CxxxCxxC. Radical SAM enzymes comprise the largest superfamily of metal-containing enzymes.
TRNA (pseudouridine54-N1)-methyltransferase (EC 2.1.1.257, TrmY, m1Psi methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:tRNA (pseudouridine54-N1)-methyltransferase. This enzyme catalyses the following chemical reaction
Sterculic acid is a cyclopropene fatty acid. It is found in various plants of the genus Sterculia, including being the main component of Sterculia foetida seed oil.
