EC Number   |
Substrates |
Organism |
Products |
Reversibility |
|---|
    4.2.1.42 | D-Galactarate |
- |
Escherichia coli |
5-Dehydro-4-deoxy-D-glucarate + H2O |
- |
? |
| 4.2.1.42 | D-Galactarate |
- |
Escherichia coli CR63MA |
5-Dehydro-4-deoxy-D-glucarate + H2O |
- |
? |
| 4.2.1.42 | D-Galactarate |
enzyme of D-glucarate catabolism |
Escherichia coli |
? |
- |
? |
| 4.2.1.42 | D-Galactarate |
enzyme of D-glucarate catabolism |
Escherichia coli CR63MA |
? |
- |
? |
| 4.2.1.42 | D-galacturonate |
low level activity |
Agrobacterium tumefaciens |
3-deoxy-D-xylo-hexarate + 3-deoxy-D-lyxo-hexarate + H2O |
- |
? |
| 4.2.1.42 | D-galacturonate |
low level activity |
Agrobacterium tumefaciens C58 / ATCC 33970 |
3-deoxy-D-xylo-hexarate + 3-deoxy-D-lyxo-hexarate + H2O |
- |
? |
| 4.2.1.42 | galactarate |
- |
Oceanobacillus iheyensis |
5-dehydro-4-deoxy D-glucarate + H2O |
- |
? |
| 4.2.1.42 | galactarate |
galactarate i.e. (2R,3S,4R,5S)-2,3,4,5-tetrahydroxyhexanedioate. The enzyme also catalyzes dehydration of L-talarate. The dehydration of L-talarate is accompanied by competing epimerization to galactarate. Little epimerization to L-talarate is observed in the dehydration of galactarate. On the basis of (1) structures of the wild type enzyme complexed with L-lyxarohydroxamate, an analogue of the enolate intermediate, and of the K197A mutant complexed with L-glucarate, a substrate for exchange of the R-proton, and (2) incorporation of solvent deuterium into galactarate in competition with dehydration, it is concluded that Lys197 functions as the galactarate-specific base and His328 functions as the L-talarate-specific base. The epimerization of L-talarate to galactarate that competes with dehydration can be rationalized by partitioning of the enolate intermediate between dehydration (departure of the 3-OH group catalyzed by the conjugate acid of His328) and epimerization (protonation on C2 by the conjugate acid of Lys197). Only galactarate and L-talarate are completely dehydrated by the enzyme. No other acid sugar results in detectable turnover |
Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 |
5-dehydro-4-deoxy-D-glucarate + H2O |
- |
? |
| 4.2.1.42 | galactarate |
- |
Salmonella enterica subsp. enterica serovar Typhimurium |
(2R,3S)-2,3-dihydroxy-5-oxohexanedioate + H2O |
- |
? |
| 4.2.1.42 | galactarate |
- |
Salmonella enterica subsp. enterica serovar Typhimurium ATCC 700720 |
(2R,3S)-2,3-dihydroxy-5-oxohexanedioate + H2O |
- |
? |
