| 英文名 |
N-acetyldemethylphosphinothricin P-methyltransferase |
| Example Structure |
 |
| 别名 |
BcpD, P-methylase, PhpK, SD_1168 |
| EC Number |
2.1.1.326 |
| CAS编号 |
|
| Comments |
The enzyme was originally characterized from bacteria that produce the tripeptides bialaphos and phosalacine, which inhibit plant and bacterial glutamine synthetases. It is a radical S-adenosyl-L-methionine (SAM) enzyme that contains a [4Fe-4S] center and a methylcob(III)alamin cofactor. According to the proposed mechanism, the reduced iron-sulfur center donates an electron to SAM, resulting in homolytic cleavage of the carbon-sulfur bond to form a 5′-deoxyadenosyl radical that abstracts the hydrogen atom from the P-H bond of the substrate, forming a phosphinate-centered radical. This radical reacts with methylcob(III)alamin to produce the methylated product and cob(II)alamin, which is reduced by an unknown donor to cob(I)alamin. A potential route for restoring the latter back to methylcob(III)alamin is a nucleophilic attack on a second SAM molecule. The enzyme acts in vivo on N-acetyl-demethylphosphinothricin-L-alanyl-L-alanine or N-acetyl-demethylphosphinothricin-L-alanyl-L-leucine, the intermediates in the biosynthesis of bialaphos and phosalacine, respectively. This transformation produces the only example of a carbon-phosphorus-carbon linkage known to occur in nature. |
| Cofactor |
methyl(III)cobalamin;iron-sulfur |
| History |
|
| Reactions |
2 S-adenosyl-L-methionine + N-acetyl-demethylphosphinothricin + reduced acceptor = S-adenosyl-L-homocysteine + 5′-deoxyadenosine + L-methionine + N-acetyl-phosphinothricin + oxidized acceptor. |
