EC Number   |
Reaction |
Reference |
|---|
    5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
- |
- |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
catalytic mechanism of ornithine 4,5-aminomutase. Substrate binding results in formation of a Schiff base between the terminal amino group of the substrate and the imine nitrogen of the PLP cofactor. Subsequent homolysis of the Co-C bond generates cob(II)alamin and the highly reactive 5'-deoxyadenosyl radical, which abstracts a hydrogen atom from the C4 of the substrate. The substrate radical intermediate then rearranges to the product-like radical intermediate via a proposed cyclic intermediate. Re-abstraction of a hydrogen atom from 5'-deoxyadenosine regenerates the 5'-deoxyadenosyl radical. Product release and recombination between cob(II)alamin and the 5'-deoxyadenosyl radical completes the catalytic cycle |
-, 747193 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
catalytic mechanism, detailed overview. The substrate forms a covalent Schiff base linkage with the imine nitrogen of the pyridoxal 5'-phosphate cofactor. In particular, Tyr187 forms a Pi-stacking interaction with the pyridine ring of pyridoxal 5'-phosphate, the guanidinium side chain of Arg297 forms a salt bridge with the alpha-carboxylate group of the substrate, and residues His225, His182, Asn226, Glu81, and Ser162 provide additional hydrogen bonding interactions with the substrate and cofactor |
747073 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
catalytic mechanism, overview |
727644 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
mechanism, overview, a gradual weakening of the electrostatic energy between the protein and the ribose leads to a progressive increase in the activation energy barrier for adenosylcobalamin Co-C bond homolysis, key role for the conserved polar glutamate residue in controlling the initial generation of radical species |
-, 727036 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
mechanism, overview, a gradual weakening of the electrostatic energy between the protein and the ribose leads to a progressive increase in the activation energy barrier for adenosylcobalamin Co?C bond homolysis, key role for the conserved polar glutamate residue in controlling the initial generation of radical species |
-, 727036 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
radical-based catalysis mechanism, closed, active enzyme form modeling, overview |
727677 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
radical-based catalysis that is initiated and propagated by the enzyme's adenosylcobalamin and pyridoxal 5'-phosphate cofactors. Following transaldimination, the Co-C bond of adenosylcobalamin undergoes homolytic rupture, generating a highly reactive carbon-centered 5'-deoxyadenosyl radical and cob(II)alamin. The 5'-deoxyadenosyl radical abstracts the C4 hydrogen atom from the D-ornithinyl-pyridoxal 5'-phosphate aldimine producing a substrate radical, which undergoes internal addition to the imine N to form an aziridylcarbinyl-pyridoxal 5'-phosphate radical adduct. Ring opening leads to formation of a product-like radical intermediate 3, which reabstracts a hydrogen atom from 5'-deoxyadenosine. Adenosylcobalamin is reformed with geminate recombination between the 5'-deoxyadenosyl radical and cob(II)alamin. Release of product from pyridoxal 5'-phosphate completes the catalytic cycle |
-, 727131 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
radical-based catalysis that is initiated and propagated by the enzyme's adenosylcobalamin and pyridoxal 5'-phosphate cofactors. Following transaldimination, the Co-C bond of adenosylcobalamin undergoes homolytic rupture, generating a highly reactive carbon-centered 5'-deoxyadenosyl radical and cob(II)alamin. The 5'-deoxyadenosyl radical abstracts the C4 hydrogen atom from the D-ornithinylpyridoxal 5'-phosphate aldimine producing a substrate radical, which undergoes internal addition to the imine N to form an aziridylcarbinyl-pyridoxal 5'-phosphate radical adduct. Ring opening leads to formation of a product-like radical intermediate 3, which reabstracts a hydrogen atom from 5'-deoxyadenosine. Adenosylcobalamin is reformed with geminate recombination between the 5'-deoxyadenosyl radical and cob(II)alamin. Release of product from pyridoxal 5'-phosphate completes the catalytic cycle |
-, 727131 |
| 5.4.3.5 | D-ornithine = (2R,4S)-2,4-diaminopentanoate |
the proposed catalytic cycle of OAM starts with substrate binding, which triggers homolytic rupture of the Co-C bond to generate cob(II)alamin and the transient 5'-deoxyadenosyl radical (AdoCH2C), which subsequently abstracts a hydrogen atom from the pyridoxal 5'-phosphate-bound substrate. This results in a pyridoxal 5'-phosphate-bound substrate radical (CYC-1) that isomerises to form a pyridoxal 5'-phosphate-bound product radical (CYC+1) via a cyclic aziridinylcarbinyl intermediate (CYC). Re-abstraction of the hydrogen atom from 5'-deoxyadenosine (AdoCH3) by CYC+1 produces AdoCH2C, which recombines with cob(II)alamin to regenerate the 5'-deoxyadenosylcobalamin Co-C bond |
747565 |
