5.4.3.5 5'-deoxyadenosylcobalamin - 747193, 747565, 748182 5.4.3.5 5'-deoxyadenosylcobalamin Km value 0.00043 652199 5.4.3.5 5'-deoxyadenosylcobalamin shows ability to produce highly reactive 5'-deoxyadenosyl radical in enzymatic environments 727644 5.4.3.5 adenosylcobalamin - 704658 5.4.3.5 adenosylcobalamin binding analysis with recombinant wild-type and mutant enzymes, overview 727036 5.4.3.5 adenosylcobalamin dependent on 693191, 727677, 747073 5.4.3.5 adenosylcobalamin paramagnetic Co2+ metal center of the cob(II)alamin cofactor 727131 5.4.3.5 additional information adenosylcobalamin-dependent ornithine 4,5-aminomutase from Clostridium sticklandii utilizes pyridoxal 5'-phosphate to interconvert D-ornithine to 2,4-diaminopentanoate via a multistep mechanism that involves two hydrogen transfer steps 747073 5.4.3.5 additional information ornithine 4,5-aminomutase is a 5'-deoxyadenosylcobalamin and pyridoxal 5'-phosphate co-dependent radical enzyme. Identification of a dynamic interface between the cobalamin and pyridoxal 5'-phosphate-binding domains, overview. Following ligand binding-induced cleavage of the Lys629-pyridoxal 5'-phosphate covalent bond, dynamic motion of the cobalamin-binding domain leads to conformational sampling of the available space. This supports radical catalysis through transient formation of a catalytically competent active state. Crucially, it appears that the formation of the state containing both a substrate/product radical and Co(II) does not restrict cobalamin domain motion 748182 5.4.3.5 additional information ornithine 4,5-aminomutase is a 5'-deoxyadenosylcobalamin and pyridoxal 5'-phosphate co-dependent radical enzyme. The conserved residues include S162 and N226, which form hydrogen bonds to the pyridine nitrogen and the phenolic group of pyridoxal 5'-phosphate, respectively. Other residues include Y187 and Y160, which flank the pyridine ring. The former aromatic side chain also forms a hydrogen bond to the pyridoxal 5'-phosphate phosphate, while the latter side chain forms a hydrogen bond to AdoCbl in a modelled closed conformation of the enzyme 747193 5.4.3.5 pyridoxal 5'-phosphate - 704658, 727677, 748182 5.4.3.5 pyridoxal 5'-phosphate covalently bound via a Schiff base (imine) to Lys629 727131 5.4.3.5 pyridoxal 5'-phosphate dependent on 693191 5.4.3.5 pyridoxal 5'-phosphate Km value 0.0015 652199 5.4.3.5 pyridoxal 5'-phosphate quantum mechanics/molecular mechanics (QM/MM) studies on the mechanism of action of cofactor pyridoxal 5'-phosphate in ornithine 4,5-aminomutase, overview 747565 5.4.3.5 pyridoxal 5'-phosphate required, important role of enzyme residue tyrosine 187, which lies planar to the pyridoxal 5'-phosphate pyridine ring. 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 pyridoxal 5'-phosphate required, Km: 0.00036 mM 2074 5.4.3.5 pyridoxal 5'-phosphate stabilizes high-energy intermediates for performing challenging 1,2-amino rearrangements between adjacent carbons, binding site structure, overview 727644 5.4.3.5 pyridoxal 5'-phosphate the protonation state of the pyridoxal 5'-phosphate cofactor has less of a role in radical-mediated chemistry compared to electrostatic interactions between the substrate and protein. Binding structure analysis and comparison with lysien 5,6-aminomutase, EC 5.4.3.3 747193 5.4.3.5 vitamin B12 - 661645 5.4.3.5 vitamin B12 required 2074 5.4.3.5 vitamin B6 - 661645