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At least 217 records · Page 12Linked to original sources

PubMed1990

Location of phosphoglycerate mutase in rat skeletal muscle. An immunocytochemical and biochemical study.

The subcellular distribution of phosphoglycerate mutase was studied by immunogold techniques. With the aid of highly affinity-purified anti-phosphoglycerate mutase antibodies, the enzyme was found in both cytosol and nucleus of rat skeletal muscle. No evidence of interaction with contractile proteins was observed in cytosol. Nuclear location was also confirmed biochemically using purified nuclear preparations from rat skeletal muscle. Only one immunoreactive nuclear band was observed by Western blot experiments and corresponded to that of phosphoglycerate mutase mobility. Activity measurements from nuclear extracts showed that 25% of total specific activity is found in the nuclei.

Animals↗

PubMed1988

Isolation and characterization of the human 2,3-bisphosphoglycerate mutase gene.

The human 2,3-bisphosphoglycerate mutase gene was isolated from genomic libraries and analyzed by Southern blots and DNA sequencing. The transcription initiation site was localized by primer extension as well as by S1 protection of the mRNA. The gene extends over 22 kilobase pairs; it is composed of two introns (8.8 and 11.5 kilobase pairs long) and three exons (84, 662, and 965 base pairs long). The second exon correlates with a functional subdomain of the protein, as shown by comparison with the yeast phosphoglycerate mutase structure. The sequence TAGAAAA was found 30 bases upstream from the transcription initiation site and could be analogous to the TATA box. A sequence homologous to the CCAAT box was found twice, at positions -75 and -178. There is no GC-rich sequence or GC box in the 5'-flanking region of the gene. Northern blot analysis indicates that the 2,3-bisphosphoglycerate mutase mRNA is detected mainly in erythroid tissues and cell lines, although it is also present in low amounts in a nonerythroid tissue. A comparison of the 5'-upstream sequences with other promoters active only in erythroid cells did not reveal any common signal that could be responsible for the "erythroid promoter."

Amino Acid Sequence↗

PubMed1988

Sequence of the human erythrocyte phosphoglycerate mutase by microsequencer and mass spectrometry.

We have previously reported the isolation in pure form of the human erythrocyte phosphoglycerate mutase isozyme B. We now report the sequence of the whole protein and the identification of its N-terminal blocking group. The protein tryptic peptides of phosphoglycerate mutase isozyme B were isolated by high performance liquid chromatography and their sequence determined by microsequencing. The sequence and the nature of the blocking group of the N-terminal tryptic peptide was shown to be N-acetyl-Ala-Ala-Tyr-Lys by mass spectrometry. Overlaps of the tryptic peptides were obtained by studying the V8 Staphylococcus aureus protease peptides of the aminoethylated phosphoglycerate mutase isozyme B either by microsequencing or by mass spectrometry. The procedure used allowed us to obtain the sequence on a very small amount of material and in a short period of time. Our data agree well with those derived from the cDNA nucleotide sequence described by Sakoda et al. (Sakoda, S., Shanske, S., DiMauro, S., and Schon, E. A. (1988) J. Biol. Chem. 263, 16899-16905). In addition, our data directly indicate that the initiation codon does not introduce a methionine as N-terminal amino acid and allowed the identification of the acetyl N-terminal group.

Amino Acid Sequence↗

PubMed1980

Purification and properties of dissociable chorismate mutase from Brevibacterium flavum.

Component B of chorismate mutase of Brevibacterium flavum, the first enzyme specific for phenylalanine and tyrosine biosynthesis, was purified to near homogeneity. The molecular weights of component B and its subunit were estimated to be 25,000 and 13,500, respectively. Component A (previously purified) or B alone did not show any chorismate mutase activity but together they showed activity. The enzyme activity was not proportional to the amount of the enzyme. The optimum pH of the reaction was 8.0. Double-reciprocal plots of the reaction rate against chorismate concentration curved upwards. S0.5 and Hill coefficient values were estimated to be 5.5 mM and 3.1, respectively. The chorismate mutase component A and 3-deoxy-D-arabino-heptulosonate 7-phosphate synthetase activities of component A were labile and were stabilized by tryptophan, dithiothreitol or cobalt ions. Phenylalanine and tyrosine inhibited the enzyme activity partially and competitively. The simultaneous presence of phenylalanine and tyrosine caused cumulative inhibition at saturated concentrations. The concentrations of phenylalanine, tyrosine, and phenylalanine plus tyrosine (each) giving 50% inhibition under the standard conditions were 0.0041, 0.095, and 0.0023 mM, respectively. Tryptophan activated the enzyme about 6-fold. The concentration giving the half-maximum activation was 0.0023 mM. Furthermore, tryptophan overcame the inhibition caused by phenylalanine and tyrosine. The tryptophan activation affected only S0.5, not the maximum velocity or the Hill coefficient. beta-2-Thienylalanine, m-fluorophenylalanine, alpha-methylphenylalanine, and phenylalanine hydroxamate inhibted the enzyme in the same way as phenylalaine, while tyrosine hydroxamate and alpha-methyltyrosine inhibited it in the same way as tyrosine. 4-Methyltryptophan, 5-fluorotryptophan, 6-fluorotryptophan, tryptophan hydroxamate, and alpha-methyltryptophan activated the enzyme in the same way as tryptophan.

Amino Acids↗

PubMed1995

[Purification of enolase and phosphoglycerate mutase from human brain and formation of a bienzymatic complex from them].

Neuron-specific enolase and phosphoglycerate mutase with specific activities of 106 and 215 U/mg, respectively, have been purified from human brain. Hydrophobic chromatography for enolase and blue Sepharose affinity chromatography for phosphoglycerate mutase were used as the last steps of purification. A heterobifunctional complex with fully preserved enolase and phosphoglycerate mutase activities was synthesized with the use of a bifunctional reagent, N-succinimidyl 3-(2-pyridyldithio)propionate. Autoantibodies to the conjugate will be used for identifying the bienzymatic complex in vivo.

Autoantibodies↗

PubMed1994

Inhibition of the human methylmalonyl-CoA mutase by various CoA-esters.

Human methylmalonyl-CoA mutase is inhibited by ethylmalonyl-CoA, cyclopropylcarbonyl-CoA carboxylate, and methylenecyclopropylacetyl-CoA, which are substrate, intermediate, and product analogs, respectively. The mode of inhibition by each analog is reversible and mixed with respect to the substrate, methylmalonyl-CoA. This implies that the inhibitors are able to bind to both free enzyme and to the enzyme-substrate complex, although with affinities that are 4.5- to 10-fold different for the two species. The Ki1 for the cyclopropylcarbonyl-CoA carboxylate (0.26 +/- 0.07 mM), is 4-fold greater than the Km(app) measured for the substrate, methylmalonyl-CoA. Additionally, ethylmalonyl-CoA functions as an alternate substrate and is metabolized to methylsuccinyl-CoA. The human mutase is a homodimer that binds 1 mol of cobalamin per subunit. So, the observed mixed inhibition kinetics by substrate analogs is curious. Our finding that methylenecyclopropylacetyl-CoA, the causative agent of Jamaican "vomiting sickness," inhibits methylmalonyl-CoA mutase, while interesting, is probably not physiologically important because of the relatively high inhibition constants (Ki1 = 0.47 +/- 0.12 mM and Ki2 = 2 +/- 0.34 mM) observed with this compound.

Acyl Coenzyme A↗

PubMed1976

Rates of phosphorylation and dephosphorylation of phosphoglycerate mutase and bisphosphoglycerate synthase.

Phosphoglycerate mutase and bisphosphoglycerate synthase (mutase) can both be phosphorylated by either glycerate-1,3-P2 or glycerate-2,3-P2 to form phosphohistidine enzymes. The present study uses a rapid quench procedure to determine if, for each enzyme, the formation of the phosphorylated enzyme and phosphate transfer from the enzyme can occur at rates consistent with the overall reactions. With bisphosphoglycerate synthase from horse red blood cells (glycerate-1,3-P2 leads to glycerate-2,3-P2) at pH 7.5, 25 degrees, phosphorylation of the enzyme appears rate-limiting, k = 13.5 s-1, compared with kcat = 12.5 s-1 for the overall synthase rate. Phosphoryl transfer from the enzyme to phosphoglycerate occurs at 38 s-1 at 4 degrees and was too fast to measure at 25 degrees. With chicken muscle phosphoglycerate mutase the half-times were too short to measure under optimal conditions. The rate of enzyme phosphorylation by glycerate-2,3-P2 at pH 5.5, 4 degrees, could account for the overall reaction rate of 170 s-1. The rate of phosphoryl transfer from the enzyme to glycerate-3-P was too rapid to measure under the same conditions. It is concluded that the phosphorylated enzymes have kinetic properties consistent with their participation as intermediates in the reactions catalyzed by these enzymes.

Animals↗

PubMed1998

Archael phosphoproteins. Identification of a hexosephosphate mutase and the alpha-subunit of succinyl-CoA synthetase in the extreme acidothermophile Sulfolobus solfataricus.

When soluble extracts from the extreme acidophilic archaeon Sulfolobus solfataricus were incubated with [gamma-32P]ATP, several radiolabeled polypeptides were observed following SDS-PAGE. The most prominent of these migrated with apparent molecular masses of 14, 18, 35, 42, 46, 50, and 79 kDa. Phosphoamino acid analysis revealed that all of the proteins contained phosphoserine, with the exception of the 35-kDa one, whose protein-phosphate linkage proved labile to strong acid. The observed pattern of phosphorylation was influenced by the identity of the divalent metal ion cofactor used, Mg2+ versus Mn2+, and the choice of incubation temperature. The 35- and 50-kDa phosphoproteins were purified and their amino-terminal sequences determined. The former polypeptide's amino-terminal sequence closely matched a conserved portion of the alpha-subunit of succinyl-CoA synthetase, which forms an acid-labile phosphohistidyl enzyme intermediate during its catalytic cycle. This identification was confirmed by the ability of succinate or ADP to specifically remove the radiolabel. The 50-kDa polypeptide's sequence contained a heptapeptide motif, Phe/Pro-Gly-Thr-Asp/Ser-Gly-Val/Leu-Arg, found in a similar position in several hexosephosphate mutases. The catalytic mechanism of these mutases involves formation of a phosphoseryl enzyme intermediate. The identity of p50 as a hexosephosphate mutase was confirmed by (1) the ability of sugars and sugar phosphates to induce removal of the labeled phosphoryl group from the protein, and (2) the ability of [32P]glucose 6-phosphate to donate its phosphoryl group to the protein.

Adenosine Diphosphate↗

PubMed1985

Chorismate mutase-prephenate dehydrogenase from Escherichia coli: cooperative effects and inhibition by L-tyrosine.

The effects of a variety of structural analogs of L-tyrosine on the mutase and dehydrogenase activities of hydroxyphenylpyruvate synthase have been investigated. From these studies it is concluded that the alpha-NH3+ alpha-COO-, and the 4-OH groups are essential for binding of L-tyrosine as an inhibitor of the dehydrogenase and that the L configuration is also essential. Dixon plots for inhibition of the dehydrogenase activity by some of these analogs were nonlinear and could be described by a velocity equation that is the ratio of quadratic polynomials (a 2/1 function). Dixon plots for inhibition of the mutase by prephenate at low concentrations of chorismate could also be described by a 2/1 function, but at low concentrations of prephenate chorismate acts as an apparent hyperbolic activator of the dehydrogenase activity. Up to concentrations of 300 microM, L-tyrosine activates the mutase but acts as a potent inhibitor of the dehydrogenase. Such data for the dehydrogenase could not be described by a 2/1 function in 1/[prephenate] but could be fitted to the Hill equation with increasing concentrations of L-tyrosine in the presence of 1.0 mM NAD yielding increasing values for the Hill number (n): in the absence of L-tyrosine, n = 1.6 +/- 0.1; at 150 microM L-tyrosine, n = 2.1 +/- 0.1; at 300 microM L-tyrosine, n = 2.3 +/- 0.4. L-Tyrosine bears a close structural resemblance to both prephenate and hydroxyphenylpyruvate, and evidence is presented which is consistent with L-tyrosine acting as a competitive inhibitor with respect to prephenate of the dehydrogenase.

Adamantane↗

PubMed1995

Coordination of a histidine residue of the protein-component S to the cobalt atom in coenzyme B12-dependent glutamate mutase from Clostridium cochlearium.

Electron paramagnetic resonance (EPR) spectroscopy of glutamate mutase from Clostridium cochlearium was performed in order to test the idea, that a histidine residue of component S replaces the dimethylbenzimidazole ligand of the Co-atom during binding of coenzyme B12 to the enzyme. The shapes and the superhyperfine splitting of the gz-lines of the Co(II) EPR spectra were used as indicators of the interaction of the axial base nitrogen with the Co-atom. A mixture of completely 15N-labelled component S, unlabelled component E, coenzyme B12 and glutamate gave slightly sharper gz-lines than that with unlabelled component S. A more dramatic change was observed in the Co(II) spectrum of the inactivated enzyme containing tightly bound cob(II)alamin, in which unlabelled component S caused a threefold superhyperfine-splitting of the gz-line, whereas the 15N-labelled protein only caused a twofold splitting, as expected for a direct interaction of a nitrogen of the enzyme with the Co-atom. By using a sample of 15N-labelled component S, in which only the histidines were 14N-labelled, the EPR spectra showed no difference to those with unlabelled component S. The experiments indeed demonstrate a replacement of the dimethylbenzimidazole ligand in coenzyme B12 by a histidine when bound to glutamate mutase. The most likely candidate is H16, which is conserved among the carbon skeleton rearranging mutases and methionine synthase.

Amino Acid Isomerases↗

PubMed1978

Chorismate mutase-prephenate dehydratase from Escherichia coli: active sites of a bifunctional enzyme.

The relationship between the active sites of the bifunctional enzyme chorismate mutase-prephenate dehydratase has been examined. Steady-state kinetic investigations of the reactions with chorismate or prephenate as substrate and studies of the overall conversion of chorismate to phenylpyruvate indicate that there are two distinct active sites. One site is responsible for the mutase activity and the other for the dehydratase activity. Studies of the overall reaction using radioactive chorismate show that prephenate, which is formed from chorismate, dissociates from the mutase site and equilibrates with the bulk medium before combining at the dehydratase site. No evidence was obtained for direct channeling of prephenate from one site to the other, or for any strong interaction between the sites.

Binding Sites↗

PubMed2005

Electronic structure studies of the adenosylcobalamin cofactor in glutamate mutase.

Glutamate mutase (GM) is a cobalamin-dependent enzyme that catalyzes the reversible interconversion of L-glutamate and L-threo-3-methylaspartate via a radical-based mechanism. To initiate catalysis, the 5'-deoxyadenosylcobalamin (AdoCbl) cofactor's Co-C bond is cleaved homolytically to generate an adenosyl radical and Co2+ Cbl. In this work, we employed a combination of spectroscopic and computational tools to evaluate possible mechanisms by which the Co-C bond is activated for homolysis. Minimal perturbations to the electronic absorption (Abs), circular dichroism (CD), and magnetic CD (MCD) spectra of AdoCbl are observed upon formation of holoenzyme, even in the presence of substrate (or a substrate analogue), indicating that destabilization of the Co3+ Cbl "ground state" is an unlikely mechanism for Co-C bond activation. In contrast, striking alterations are observed in the spectroscopic data of the post-homolysis product Co2+ Cbl when bound to glutamate mutase in the presence of substrate (or a substrate analogue) as compared to unbound Co2+ Cbl. These enzymatic perturbations appear to most strongly affect the metal-to-ligand charge-transfer transitions of Co2+ Cbl, suggesting that the cofactor/active-site interactions give rise to a fairly uniform stabilization of the Co 3d orbitals. Remarkable similarities between the results obtained in this study and those reported previously for the related Cbl-dependent isomerase methylmalonyl-CoA mutase indicate that a common mechanism by which the cofactor's Co-C bond is activated for homolytic cleavage may be operative for all base-off/His-on Cbl-dependent isomerases.

Circular Dichroism↗

PubMed1997

How enzymes control the reactivity of adenosylcobalamin: effect on coenzyme binding and catalysis of mutations in the conserved histidine-aspartate pair of glutamate mutase.

Glutamate mutase is one of a group of adenosylcobalamin-dependent enzymes that catalyze unusual isomerizations that proceed through the formation of radical intermediates. It shares a structurally similar cobalamin-binding domain with methylcobalamin-dependent methionine synthase. In particular, both proteins contain the "DXHXXG" cobalamin-binding motif, in which the histidine provides the axial ligand to cobalt. The effects of mutating the conserved histidine and aspartate residues in methionine synthase have recently been described [Jarrett, J. T., Amaratunga, M., Drennan, C. L., Scholten, J. D., Sands, R. H., Ludwig, M. L., & Matthews, R. G. (1996) Biochemistry 35, 2464-2475]. Here, we describe how similar mutations in the "DXHXXG" motif of glutamate mutase affect coenzyme binding and catalysis in an adenosylcobalamin-dependent reaction. The mutations made in the MutS subunit of glutamate mutase were His16Gly, His16Gln, Asp14Asn, Asp14Glu, and Asp14Ala. All the mutations affect, in varying degrees, the rate of catalysis, the affinity of the protein for the coenzyme, and the coordination of cobalt. Mutations of either Asp14 or His16 decrease k(cat) by 1000-fold, and whereas cob(II)alamin accumulates as an intermediate in the wild-type enzyme, it does not accumulate in the mutants, suggesting the rate-determining step is altered. The apparent Kd for adenosylcobalamin is raised by about 50-fold when His16 is mutated and by 5-10-fold when Asp16 is mutated. There are extensive differences between the UV-visible spectra of wild-type and mutant holoenzymes, indicating that the mutant enzymes coordinate cobalt less well. Overall, the properties of these mutants differ quite markedly from those observed when similar mutations were introduced into methionine synthase.

Amino Acid Isomerases↗

PubMed1999

Insight into the mechanism of phosphoenolpyruvate mutase catalysis derived from site-directed mutagenesis studies of active site residues.

PEP mutase catalyzes the conversion of phosphoenolpyruvate (PEP) to phosphonopyruvate in biosynthetic pathways leading to phosphonate secondary metabolites. A recent X-ray structure [Huang, K., Li, Z., Jia, Y., Dunaway-Mariano, D., and Herzberg, O. (1999) Structure (in press)] of the Mytilus edulis enzyme complexed with the Mg(II) cofactor and oxalate inhibitor reveals an alpha/beta-barrel backbone-fold housing an active site in which Mg(II) is bound by the two carboxylate groups of the oxalate ligand and the side chain of D85 and, via bridging water molecules, by the side chains of D58, D85, D87, and E114. The oxalate ligand, in turn, interacts with the side chains of R159, W44, and S46 and the backbone amide NHs of G47 and L48. Modeling studies identified two feasible PEP binding modes: model A in which PEP replaces oxalate with its carboxylate group interacting with R159 and its phosphoryl group positioned close to D58 and Mg(II) shifting slightly from its original position in the crystal structure, and model B in which PEP replaces oxalate with its phosphoryl group interacting with R159 and Mg(II) retaining its original position. Site-directed mutagenesis studies of the key mutase active site residues (R159, D58, D85, D87, and E114) were carried out in order to evaluate the catalytic roles predicted by the two models. The observed retention of low catalytic activity in the mutants R159A, D85A, D87A, and E114A, coupled with the absence of detectable catalytic activity in D58A, was interpreted as evidence for model A in which D58 functions in nucleophilic catalysis (phosphoryl transfer), R159 functions in PEP carboxylate group binding, and the carboxylates of D85, D87 and E114 function in Mg(II) binding. These results also provide evidence against model B in which R159 serves to mediate the phosphoryl transfer. A catalytic motif, which could serve both the phosphoryl transfer and the C-C cleavage enzymes of the PEP mutase superfamily, is proposed.

Amino Acid Motifs↗

PubMed1996

Adenosylcobalamin-dependent glutamate mutase: properties of a fusion protein in which the cobalamin-binding subunit is linked to the catalytic subunit.

Adenosylcobalamin-dependent glutamate mutase (EC 5.4.99.1) from Clostridium tetanomorphum comprises two protein components, MutE and MutS. The formation of the holoenzyme is a kinetically complex process that involves the co-operative association of MutS, MutE and adenosylcobalamin. The MutS portion of the cobalamin-binding site is conserved within a group of adenosylcobalamin-dependent enzymes that catalyse similar isomerizations. However, in contrast with glutamate mutase, in these other enzymes the cobalamin-binding region represented by MutS is present as a C-terminal domain. We have investigated the effect on the structural and kinetic properties of glutamate mutase of linking MutS to the C-terminus of MutE. Kinetic analysis of this protein, MutES, showed, unexpectedly, that enzyme activity was still co-operatively dependent on protein concentration. The Km for L-glutamate was unchanged from the wild type, whereas Vmax was decreased to approx. one-thirtieth and the Km for coenzyme increased approx. 10-fold. Investigation of the quaternary structure of MutES by equilibrium ultra-centrifugation indicated that the protein existed in equilibrium between monomeric and dimeric forms. Thus linking MutE and MutS together seems to substantially weaken the contacts that are responsible for the dimerization of MutE. The two domains of the MutES monomer seem unable to communicate, so that active enzyme is formed by the intermolecular association of two MutES subunits in a co-operative manner.

Amino Acid Isomerases↗

PubMed2000

Characterization of hydroxylaminobenzene mutase from pNBZ139 cloned from Pseudomonas pseudoalcaligenes JS45. A highly associated SDS-stable enzyme catalyzing an intramolecular transfer of hydroxy groups.

Hydroxylaminobenzene mutase is the enzyme that converts intermediates formed during initial steps in the degradation of nitrobenzene to a novel ring-fission lower pathway in Pseudomonas pseudoalcaligenes JS45. The mutase catalyzes a rearrangement of hydroxylaminobenzene to 2-aminophenol. The mechanism of the reactions and the properties of the enzymes are unknown. In crude extracts, the hydroxylaminobenzene mutase was stable at SDS concentrations as high as 2%. A procedure including Hitrap-SP, Hitrap-Q and Cu(II)-chelating chromatography was used to partially purify the enzyme from an Escherichia coli clone. The partially purified enzyme was eluted in the void volume of a Superose-12 gel-filtration column even in the presence of 0.05% SDS in 25 mM Tris/HCl buffer, which indicated that it was highly associated. When the enzymatic conversion of hydroxylaminobenzene to 2-aminophenol was carried out in 18O-labeled water, the product did not contain 18O, as determined by GC-MS. The results indicate that the reaction proceeded by intramolecular transfer of the hydroxy group from the nitrogen to the C-2 position of the ring. The mechanism is clearly different from the intermolecular transfer of the hydroxy group in the non-enzymatic Bamberger rearrangement of hydroxylaminobenzene to 4-aminophenol and in the enzymatic hydroxymutation of chorismate to isochorismate.

Aminophenols↗

PubMed1998

Crystallization and preliminary X-ray analysis of recombinant glutamate mutase and of the isolated component S from Clostridium cochlearium.

Glutamate mutase [varepsilon2sigma2(B12)1] was reconstituted by incubating purified components E (varepsilon2) and S (sigma2) from Clostridium cochlearium, both produced in Escherichia coli, with either aquo- or cyanocobalamin. The inactive glutamate mutase obtained was crystallized with polyethyleneglycol 4000 as precipitant. Crystals are monoclinic with space group P21 and have cell dimensions a = 64.6, b = 113.2, c = 108.4 A and beta = 96.0 degrees for the glutamate mutase reconstituted with aquocobalamin. They diffract to a resolution of at least 2.7 A. Isolated component S was crystallized in the presence of an excess of cyanocobalamin, yielding red crystals of space group I422 with unit-cell dimensions of a = b = 69.9 and c = 107.1 A. The crystals diffract to about 3.2 A resolution. Native data sets were collected for both crystal forms.

Bacterial Proteins↗

PubMed1989

Assay and purification of the adenosylcobalamin-dependent 2-methyleneglutarate mutase from Clostridium barkeri.

A continuous spectrophotometric assay was developed for the adenosylcobalamin-dependent 2-methyleneglutarate mutase from Clostridium barkeri. Thereby the product (R)-3-methylitaconate is converted by the delta-isomerase from the same organism to 2,3-dimethylmaleate which absorbs at 240 nm, much higher than both parent compounds (delta epsilon = 3.7 mM-1.cm-1). In addition a discontinuous assay using the facile formation of 2,3-dimethylmaleic anhydride in aqueous solution at pH 0-1 (delta epsilon = 4.0 mM-1.cm-1 at 256 nm) was established. The mutase and the isomerase were purified together by chromatography on quaternary-amine-Sepharose (Q-Sepharose) and on cyanocobalamin-agarose. The enzymes were separated and obtained in homogenous forms by preparative PAGE in non-denaturing buffer. Both enzymes appear to be homotetramers with subunits of 70 kDa (mutase) and 50 kDa (isomerase). The equilibrium constants for both reactions were determined at I = 0.1 M and 25 degrees C: K1, app = [(R)-3-methylitaconate].[2-methyleneglutarate]-1 = 0.26 +/- 0.04, K2,app = [2,3-dimethylmaleate].[(R)-3-methylitaconate]-1 = 7.40 +/- 0.21.

Carbon-Carbon Double Bond Isomerases↗