ID 2.1.1.326 DE N-acetyl-demethylphosphinothricin P-methyltransferase. AN P-methylase. CA AH2 + N-acetyl-demethyl-L-phosphinothricin + 2 S-adenosyl-L-methionine = CA 5'-deoxyadenosine + A + 2 H(+) + L-methionine + N-acetyl-L- CA phosphinothricin + S-adenosyl-L-homocysteine. CC -!- The enzyme was originally characterized from bacteria that produce CC the tripeptides bialaphos and phosalacine, which inhibit plant and CC bacterial glutamine synthetases. CC -!- It is a radical S-adenosyl-L-methionine (SAM) enzyme. CC -!- According to the proposed mechanism, the reduced iron-sulfur center CC donates an electron to SAM, resulting in homolytic cleavage of the CC carbon-sulfur bond to form a 5'-deoxyadenosyl radical that abstracts CC the hydrogen atom from the P-H bond of the substrate, forming a CC phosphinate-centered radical. CC -!- This radical reacts with methylcob(III)alamin to produce the CC methylated product and cob(II)alamin, which is reduced by an unknown CC donor to cob(I)alamin. CC -!- A potential route for restoring the latter back to CC methylcob(III)alamin is a nucleophilic attack on a second SAM CC molecule. CC -!- The enzyme acts in vivo on N-acetyl-demethylphosphinothricin-L- CC alanyl-L-alanine or N-acetyl-demethylphosphinothricin-L-alanyl-L- CC leucine, the intermediates in the biosynthesis of bialaphos and CC phosalacine, respectively. CC -!- This transformation produces the only example of a carbon-phosphorus- CC carbon linkage known to occur in nature. //