4X1C: Crystal Structure Of 4-ot From Pseudomonas Putida Mt-2 With An Enamine Adduct On The N-terminal Proline At 1.7 Angstrom Resolution

The enzyme 4-oxalocrotonate tautomerase (4-OT), which has a catalytic N-terminal proline residue (Pro1), can promiscuously catalyze various carbon-carbon bond-forming reactions, including aldol condensation of acetaldehyde with benzaldehyde to yield cinnamaldehyde, and Michael-type addition of acetaldehyde to a wide variety of nitroalkenes to yield valuable gamma-nitroaldehydes. To gain insight into how 4-OT catalyzes these unnatural reactions, we carried out exchange studies in D2 O, and X-ray crystallography studies. The former established that H-D exchange within acetaldehyde is catalyzed by 4-OT and that the Pro1 residue is crucial for this activity. The latter showed that Pro1 of 4-OT had reacted with acetaldehyde to give an enamine species. These results provide evidence of the mechanism of the 4-OT-catalyzed aldol and Michael-type addition reactions in which acetaldehyde is activated for nucleophilic addition by Pro1-dependent formation of an enamine intermediate.
PDB ID: 4X1CDownload
MMDB ID: 127739
PDB Deposition Date: 2014/11/24
Updated in MMDB: 2015/03
Experimental Method:
x-ray diffraction
Resolution: 1.7  Å
Source Organism:
Similar Structures:
Biological Unit for 4X1C: hexameric; determined by author and by software (PISA)
Molecular Components in 4X1C
Label Count Molecule
Proteins (6 molecules)
2-hydroxymuconate Tautomerase(Gene symbol: xylH)
Molecule annotation
2-hydroxymuconate Tautomerase(Gene symbol: xylH)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

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