Also acts on thioethers longer in chain length on the oxo side, e.g. 2-oxobutyl-CoM, but this portion must be attached to CoM (2-sulfanylethane-1-sulfonate); no CoM analogs will substitute. This enzyme forms component II of a four-component enzyme system {comprising EC 4.4.1.23 (2-hydroxypropyl-CoM lyase; component I), EC 1.8.1.5 [2-oxopropyl-CoM reductase (carboxylating); component II], EC 1.1.1.268 [2-(R)-hydroxypropyl-CoM dehydrogenase; component III] and EC 1.1.1.269 [2-(S)-hydroxypropyl-CoM dehydrogenase; component IV]} that is involved in epoxyalkane carboxylation in Xanthobacter sp. strain Py2.
2-kpcc, nadph:2-ketopropyl-coenzyme m oxidoreductase/carboxylase, 2-ketopropyl coenzyme m oxidoreductase/carboxylase, 2-ketopropyl-coenzyme m oxidoreductase/carboxylase, more
reaction mechanism for 2-KPCC begins with formation of enzyme-substrate disulfide adduct by the reduced form of the redox active disulfide. This step is followed by release of enolacetone anion intermediates for 2-KPCC. The primary catalytic fate of the enolacetone intermediate for the wild-type (Phe501) or variant (His501) 2-KPCC is acetoacetate or acetone, respectively
Also acts on thioethers longer in chain length on the oxo side, e.g. 2-oxobutyl-CoM, but this portion must be attached to CoM (2-sulfanylethane-1-sulfonate); no CoM analogs will substitute. This enzyme forms component II of a four-component enzyme system {comprising EC 4.4.1.23 (2-hydroxypropyl-CoM lyase; component I), EC 1.8.1.5 [2-oxopropyl-CoM reductase (carboxylating); component II], EC 1.1.1.268 [2-(R)-hydroxypropyl-CoM dehydrogenase; component III] and EC 1.1.1.269 [2-(S)-hydroxypropyl-CoM dehydrogenase; component IV]} that is involved in epoxyalkane carboxylation in Xanthobacter sp. strain Py2.
i.e. 2-ketopropyl-CoM, comparison of enzyme structure with and without bound substrate, binding of 2-ketopropyl-coenzyme M induces a conformational change resulting in collapse of the substrate access channel, substrate binding site structure analysis
reversible inhibitor, time-dependent inactivator of dithiothreitol-reduced 2-ketopropyl-CoM carboxylase/oxidoreductase, where the redox active cysteines are in the free thiol forms, does not inactivate air-oxidized 2-ketopropyl-CoM carboxylase/oxidoreductase, where the redox active cysteine pair is in the disulfide form. Inactivation leads to covalent modification of the interchange thiol residue C82. The flavin thiol Cys87 is not alkylated by 2-bromoethanesulfonate under reducing conditions, and no amino acid residues are modified by 2-bromoethanesulfonate in the oxidized enzyme
the enzyme belongs to the disulfide oxidoreductase (DSOR) family of enzymes. The characteristic His-Glu catalytic dyad of the DSOR family is replaced in 2-ketopropyl coenzyme M oxidoreductase/carboxylase (2-KPCC) uniquely by the residues Phe-His, potentially to eliminate proton-donating groups at a key position in the active site. These differences in 2-KPCC are key in discriminating between carbon dioxide and protons as attacking electrophiles
2-oxopropylcoenzyme M oxidoreductase/carboxylase (2-KPCC) catalyzes the reductive cleavage and carboxylation of 2-oxopropyl coenzyme M (2-KPC) to form acetoacetate and concomitantly regenerate CoM (2-mercaptoethanesulfonate)
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
enzyme free or bound to substrate 2-ketopropyl-CoM, X-ray structure determination and analysis at 1.6-3.5 A resolution, multiple isomorphous replacement and anomalous scattering using four weak heavy atom derivatives
in complex with acetoacetate and 2-mercaptoethanesulfonate. In the substrate encapsulated state of the enzyme, CO2 is bound at the base of a narrow hydrophobic substrate access channel. The base of the channel is demarcated by a transition from a hydrophobic to hydrophilic environment where CO2 is located in position for attack on the carbanion of the ketopropyl group of the substrate to ultimately produce acetoacetate. This binding mode effectively discriminates against H2O and prevents protonation of the ketopropyl leaving group
mutagenesis of the flavin thiol, results in an inactive enzyme for steady-state redox-dependent reactions, but this variant catalyzes a single-turnover reaction producing a 0.8:1 ratio of product to enzyme. Redox-independent acetoacetate decarboxylation is not decreased
the mutant shows 10% acetoacetate production activity compared to the wild type enzyme. The overall rate of NADPH turnover remains relatively unchanged in the F501H variant relative to wild type. Moreover, acetone formation by F501H is comparable in rate to the carboxylation reaction catalyzed by wild type enzyme and leading to acetoacetate
mutagenesis of the histidine proximal to the ordered water molecule, leads to nearly complete loss of redox-dependent reactions. Redox-independent acetoacetate decarboxylation is not decreased
the mutant shows 37% acetoacetate production activity compared to the wild type enzyme. NADPH turnover is around 1.5fold slower in H506E versus wild type enzyme
mutagenesis of the distal histidine residue, reduces the redox-dependent activities by 58 to 76%. Redox-independent acetoacetate decarboxylation is not decreased
site-directed mutagenesis of the catalytic dyad, substitution of the Phe-His active site residues by the canonical residues results in production of higher relative concentrations of acetone versus the natural product acetoacetate. Replacement of the His-Glu dyad from DSORs with Phe-His is critical for specifying carboxylation chemistry in enzyme 2-KPCC
Characterization of five catalytic activities associated with the NADPH:2-ketopropyl-coenzyme M [2-(2-ketopropylthio)ethanesulfonate] oxidoreductase/carboxylase of the Xanthobacter strain Py2 epoxide carboxylase system
Structural basis for CO2 fixation by a novel member of the disulfide oxidoreductase family of enzymes, 2-ketopropyl-coenzyme M oxidoreductase/carboxylase
Mechanistic implications of the structure of the mixed-disulfide intermediate of the disulfide oxidoreductase, 2-ketopropyl-coenzyme M oxidoreductase/carboxylase
Roles of the redox-active disulfide and histidine residues forming a catalytic dyad in reactions catalyzed by 2-ketopropyl coenzyme M oxidoreductase/carboxylase