Abstract
The enzymatic cleavage of C-C bonds in beta-diketones is, comparatively, a little studied biochemical process, but one that has important relevance to human metabolism, bioremediation and preparative biocatalysis. In recent studies, four types of enzymes have come to light that cleave C-C bonds in the beta-diketone functionality using different chemical mechanisms. OPH [oxidized poly(vinyl alcohol) hydrolase from Pseudomonas sp. strain VM15C], which cleaves nonane-4,6-dione to butyrate and pentan-2-one is a serine-triad hydrolase. Dke1 (diketone-cleaving enzyme from Acinetobacter johnsonii) is a dioxygenase, cleaving acetylacetone to methylglyoxal and acetate. Fumarylacetoacetate hydrolase cleaves fumarylacetoacetate to fumarate and acetoacetate using a water molecule, activated by a catalytic His/Asp dyad, aided by a calcium ion that both chelates the enol acid form of the substrate and indirectly positions the water for nucleophilic attack at a carbonyl group. 6-Oxocamphor hydrolase cleaves nonenolizable cyclic beta-diketones and is a homologue of the crotonase superfamily, employing a catalytic His/Asp dyad to activate a water molecule for nucleophilic attack at a carbonyl group on one prochiral face of the diketone substrate, effecting desymmetrizations of symmetrical substrates.
| Original language | English |
|---|---|
| Pages (from-to) | 721-730 |
| Number of pages | 10 |
| Journal | Biochemical journal |
| Volume | 388 |
| DOIs | |
| Publication status | Published - 15 Jun 2005 |
Keywords
- catalytic triad
- crotonase
- beta-diketone
- dioxygenase
- hydrolase
- polyketide
- POLYVINYL ALCOHOL)-DEGRADING ENZYME
- RETRO-CLAISEN REACTION
- CRYSTAL-STRUCTURE
- CROTONASE SUPERFAMILY
- PSEUDOMONAS SP
- ANGSTROM RESOLUTION
- ACINETOBACTER-JOHNSONII
- SUBSTRATE-SPECIFICITY
- DEGRADING ENZYME
- CLEAVING ENZYME