4X19

Crystal structure of native 4-OT from Pseudomonas putida mt-2 at 1.94 Angstrom

Summary for 4X19

• Entry DOI: 10.2210/pdb4x19/pdb
• Descriptor: 2-hydroxymuconate tautomerase, COBALT HEXAMMINE(III) (3 entities in total)
• Functional Keywords: 4-oxalocrotonate tautomerase, beta-alpha-beta structural motif, tautomerase superfamily, isomerase
• Biological source: Pseudomonas putida
• Total number of polymer chains: 30
• Total formula weight: 204816.26

Authors

Thunnissen, A.M.W.H.,Poddar, H. (deposition date: 2014-11-24, release date: 2015-03-11, Last modification date: 2024-01-10)

Primary citation

Poddar, H.,Rahimi, M.,Geertsema, E.M.,Thunnissen, A.M.,Poelarends, G.J.
Evidence for the Formation of an Enamine Species during Aldol and Michael-type Addition Reactions Promiscuously Catalyzed by 4-Oxalocrotonate Tautomerase.
Chembiochem, 16:738-741, 2015

PubMed Abstract: 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 γ-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.

PubMed: 25728471
DOI: 10.1002/cbic.201402687

Experimental method

X-RAY DIFFRACTION (1.944 Å)