Cofactors

There are no Cofactors for this Enzyme

Reaction Mechanism

hydroxyacylglutathione hydrolase By Reference

Glyoxalase II participates in the cellular detoxification of cytotoxic and mutagenic 2-oxoaldehydes. Glyoxalase I converts methylglyoxal (a cytotoxic byproduct of many cellular reactions) and glutathione into S-D-lactoylglutathione (SLG) which is also cytotoxic; the role of glyoxalase II is to hydrolyse SLG into D-lactic acid and glutathione.

The substrate of this reaction is the product of Lactoylglutathione lyase, an enzyme which catalyses the initial steps in detoxifying methyl-glyoxyl. This enzyme regnerates the glutathione cofactor utilised by lactoylglutathione lyase.




• Summary
• Step 1
• Step 2
• Step 3
• Step 4
• Products

Glyoxalase II has a binuclear centre that has affinity for both Zn(II) and Fe(II) and is functional with either metal in either of its metal-binding sites. Both metals coordinate a bridging hydroxide ion. This hydroxide nucleophile attacks the carbonyl carbon of the thioester group of SLG. A tetrahedral intermediate is formed. Metal 1 stabilises the negative charge forming on the thioester oxygen, and metal 2 stabilises the negative charge forming on the thioester sulphur (thus making the thiolate anion a better leaving group). The tetrahedral intermediate collapses. Lactic acid and glutathione (still bound to metal 2 as a thiolate) are formed. Asp58 accepts a proton from the bridging oxygen to generate the lactate, this proton is then transferred to the thiolate to form glutathione. The products are released and new water bridges the zinc ions, the water is deprotonated by Asp58 regenerating the active site.

Catalytic Residues

AA	Uniprot	Uniprot Resid	PDB	PDB Resid
Asp	Q16775	106	1qh5	58
Asp	Q16775	182	1qh5	134
His	Q16775	102	1qh5	54
His	Q16775	104	1qh5	56
His	Q16775	107	1qh5	59
His	Q16775	158	1qh5	110
His	Q16775	221	1qh5	173

Step Components

native state of cofactor regenerated, bimolecular nucleophilic addition, proton transfer, native state of enzyme regenerated, overall reactant used, unimolecular elimination by the conjugate base, overall product formed



Step 1.

Zinc activate water attacked the carbonyl carbon of the (R)-S-lactoylglutathione substrate in a nucleophilic addition, forming a tetrahedral intermediate.



Step 2.

The tetrahedral intermediate collapses releasing the (R)-lactate product and the thiolate form of glutathione. Asp58 accepts a proton from the bridging oxygen.



Step 3.

The thiolate of glutathione deprotonates Asp58, regenerating the glutathione cofactor used in the initial formation of hydroacetylglutathione.



Step 4.

Asp58 deprotonates a new bridging water molecule regenerating the active site. This proton can then be transferred from Asp58 to solution.



Products.

The products of the reaction.

View Reaction Mechanisms in M-CSA

Reaction Parameters

• Kinetic Parameters

  Organism	KM Value [mM]	Substrate	Comment
  Salmonella enterica	1.8	S-D-lactoylglutathione	at pH 7.5 and 30°C
  Plasmodium falciparum	11	S-D-lactoylglutathione	mutant R257D, at 25°C, in 100 mM MOPS/NaOH, pH 6.8
  Leishmania infantum	180	S-D-lactoyltrypanothione	wild type protein, pH not specified in the publication, temperature not specified in the publication
  Saccharomyces cerevisiae	710	S-D-mandeloylglutathione	pH not specified in the publication, temperature not specified in the publication
  Oryza sativa	2000	S-Lactoylglutathione	pH and temperature not specified in the publication

  View all in Brenda
• Temperature

  Organism	Temperature Range	Comment
  Cyberlindnera mrakii	25 - 55	25°C: about 60% of maximal activity, 55°C: about 70% of maximal activity

• pH

  Organism	pH Range	Comment
  Oryza sativa	6 - 8
  Brassica juncea	6 - 8.5
  Nostoc sp. PCC 7120 = FACHB-418	6.5 - 8	enhanced enzyme activity in the pH range of 6.5-8.0
  Arabidopsis thaliana	7 - 9	saturation kinetic behavior for the thioester hydrolysis reaction. At pH 9.0 ligand exchange at the zinc center via deprotonation of the alpha-hydroxy group of the thioester to give an equilibrium amount of a zinc alkoxide species

Associated Proteins

Citations

• Proline-mediated activation of glyoxalase II improve methylglyoxal detoxification in Oryza sativa L. under chromium injury: Clarification via vector analysis of enzymatic activities and gene expression.
• Catalytic Reaction Mechanism of Glyoxalase II: A Quantum Mechanics/Molecular Mechanics Study.
• Identification of HAGHL as a novel metabolic oncogene regulating human colorectal cancer progression.
• Origin, Diversity, and Multiple Roles of Enzymes with Metallo-β-Lactamase Fold from Different Organisms.
• Metallo-Beta-Lactamase-like Encoding Genes in Candidate Phyla Radiation: Widespread and Highly Divergent Proteins with Potential Multifunctionality.
• Non-coding regions of nuclear-DNA-encoded mitochondrial genes and intergenic sequences are targeted by autoantibodies in breast cancer.
• MicroRNA Expression Prior to Biting in a Vector Mosquito Anticipates Physiological Processes Related to Energy Utilization, Reproduction and Immunity.
• Genome-wide analysis and expression profiling of glyoxalase gene families in oat (Avena sativa) indicate their responses to abiotic stress during seed germination.
• Glyoxalase 2: Towards a Broader View of the Second Player of the Glyoxalase System.
• Lipid and Protein Oxidation of Brown Rice and Selenium-Rich Brown Rice during Storage.
• Quantification of cytosol and membrane proteins in rumen epithelium of sheep with low or high CH4 emission phenotype.