GO:0106008 2-oxoglutaramate amidase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0106008 (2-oxoglutaramate amidase activity) catalyzes the hydrolysis of 2-oxoglutaramate to 2-oxoglutarate and ammonia, a reaction that completes the transaminase-omega-amidase pathway.
• The enzyme responsible is omega-amidase, encoded in humans by NIT2 (Nit2), a putative tumor suppressor that is functionally coupled with glutamine transaminases.
• The pathway matters because it disposes of the potentially toxic metabolite 2-oxoglutaramate while regenerating 2-oxoglutarate, a central Krebs-cycle intermediate and co-substrate for many dioxygenases.
• In endothelial cells the transaminase-omega-amidase pathway acts as an oxidative-stress sensor that controls glutamine metabolism and alpha-ketoglutarate levels.
• Altered 2-oxoglutaramate and alpha-ketoglutarate levels are measurable in chronic hepatoencephalopathy, indicating clinical relevance of this activity.
• NIT2/omega-amidase can be produced recombinantly and used for preparative biocatalytic synthesis of alpha-ketoglutaramate, making it a tractable experimental target.
Description
GO:0106008, 2-oxoglutaramate amidase activity, is a molecular function that catalyzes the hydrolysis of 2-oxoglutaramate to 2-oxoglutarate and ammonia. This activity is the terminal step of the transaminase-omega-amidase pathway, in which glutamine transaminases first convert glutamine and a keto acid into a 2-oxo acid and 2-oxoglutaramate, and omega-amidase then removes the amide nitrogen to release 2-oxoglutarate. The enzyme responsible for this activity in humans is omega-amidase, encoded by NIT2 (also known as Nit2), which was identified as the enzyme functionally coupled with glutamine transaminases and as a putative tumor suppressor. Because 2-oxoglutarate is a central Krebs-cycle intermediate and an essential co-substrate for many dioxygenases, the amidase step links amino-acid nitrogen handling to broad metabolic and epigenetic regulation. Researchers study GO:0106008 to understand how cells detoxify 2-oxoglutaramate, how they maintain alpha-ketoglutarate pools, and how loss of this activity may contribute to metabolic disease and cancer.
2-oxoglutaramate amidase activity At A Glance
| GO ID | GO:0106008 |
|---|---|
| GO term | 2-oxoglutaramate amidase activity |
| Ontology | molecular_function |
| Synonym | none listed in QuickGO |
| Definition | Catalysis of the reaction: 2-oxoglutaramate + H2O = 2-oxoglutarate + NH3 |
| Reaction type | Hydrolytic deamidation of an alpha-keto acid amide |
| Representative enzyme | Omega-amidase / Nit2 (human NIT2) |
| Pathway context | Transaminase-omega-amidase pathway coupled to glutamine transaminases |
| Key products | 2-oxoglutarate (alpha-ketoglutarate) and ammonia |
What Is GO:0106008?
In simple terms, 2-oxoglutaramate amidase activity is the enzyme activity that cuts an amide group off 2-oxoglutaramate, releasing ammonia and leaving 2-oxoglutarate. Formally, GO:0106008 describes catalysis of the reaction 2-oxoglutaramate + H2O = 2-oxoglutarate + NH3, as defined in QuickGO. This is a hydrolytic deamidation reaction: a water molecule attacks the amide carbon of 2-oxoglutaramate, ammonia is eliminated, and the product is the alpha-keto acid 2-oxoglutarate. The activity is attributed to omega-amidase (Nit2 in humans), which is functionally coupled with glutamine transaminases in the transaminase-omega-amidase pathway.
Why Is 2-oxoglutaramate amidase activity Important in Cell Biology?
2-oxoglutaramate amidase activity is important because it sits at the intersection of nitrogen disposal and central carbon metabolism. By converting 2-oxoglutaramate to 2-oxoglutarate, the enzyme both removes a metabolite that can accumulate when glutamine transamination is active and regenerates alpha-ketoglutarate, a molecule required for the Krebs cycle and for many dioxygenase reactions. In endothelial cells, the transaminase-omega-amidase pathway has been shown to sense oxidative stress and to control glutamine metabolism and alpha-ketoglutarate levels, linking this single enzymatic step to redox biology and vascular function. Because the enzyme is a putative tumor suppressor, its activity is also relevant to cancer biology and to metabolite-repair pathways that protect cells from damaged metabolites.
• Completes the transaminase-omega-amidase pathway by removing the amide nitrogen from 2-oxoglutaramate.
• Regenerates 2-oxoglutarate, a central Krebs-cycle intermediate and dioxygenase co-substrate.
• Prevents accumulation of 2-oxoglutaramate, a potentially toxic metabolite of glutamine transamination.
• Acts as part of an oxidative-stress-sensing module that controls glutamine metabolism in endothelial cells.
• Is encoded by NIT2, a putative tumor suppressor, connecting the activity to cancer biology.
• Is mechanistically related to metabolite-repair enzymes such as Nit1, which hydrolyzes deaminated glutathione.
• Provides a biocatalytic route to preparative alpha-ketoglutaramate for research and diagnostic use.
• Can be produced recombinantly in Escherichia coli for structural and kinetic studies.
• Altered alpha-ketoglutarate and alpha-ketoglutaramate levels are associated with chronic hepatoencephalopathy progression.
• Its active site and catalytic mechanism have been characterized by kinetics and molecular dynamics simulation.
Molecular Mechanism of 2-oxoglutaramate amidase activity
Substrate recognition and binding of 2-oxoglutaramate
In simple terms: The enzyme first grabs the 2-oxoglutaramate molecule and holds it in place.
Omega-amidase binds 2-oxoglutaramate, the alpha-keto acid amide produced when a glutamine transaminase transfers the amino group of glutamine to a keto acid acceptor. Structural and kinetic studies of human Nit2/omega-amidase have defined the catalytic active site that accommodates this substrate and have used kinetic assays together with molecular dynamics simulation to probe how binding positions the amide for hydrolysis. The functional coupling with glutamine transaminases means that substrate supply is tightly linked to transamination flux.
Hydrolytic deamidation and ammonia release
In simple terms: Water is used to split off the amide group, releasing ammonia.
The catalytic step is a hydrolysis: 2-oxoglutaramate + H2O = 2-oxoglutarate + NH3, as defined for GO:0106008. The enzyme catalyzes attack of water on the amide carbon, eliminating ammonia and yielding 2-oxoglutarate. Kinetic characterization of human Nit2/omega-amidase supports this hydrolytic mechanism and has been used to define the active-site residues involved. The ammonia released in this step represents nitrogen that has been removed from the original glutamine skeleton via the coupled transaminase reaction.
Product release and regeneration of 2-oxoglutarate
In simple terms: The finished product, 2-oxoglutarate, is released for use elsewhere in the cell.
After hydrolysis, the enzyme releases 2-oxoglutarate (alpha-ketoglutarate), a central Krebs-cycle intermediate and a required co-substrate for many dioxygenases. In endothelial cells, this pathway has been shown to control alpha-ketoglutarate levels and glutamine metabolism and to act as an oxidative-stress sensor. The released 2-oxoglutarate can therefore feed both energy metabolism and signaling or epigenetic reactions that depend on alpha-ketoglutarate availability.
Coupling to glutamine transaminases in the transaminase-omega-amidase pathway
In simple terms: This enzyme works as the second half of a two-enzyme assembly line that processes glutamine.
Omega-amidase is functionally coupled with glutamine transaminases, which generate 2-oxoglutaramate from glutamine and a keto acid acceptor. This coupling means that the amidase step is not isolated but is part of a pathway that senses and responds to metabolic state, including oxidative stress in endothelial cells. The identification of omega-amidase as the enzyme functionally coupled with glutamine transaminases established this pathway architecture and linked it to the putative tumor suppressor Nit2.
Relationship to metabolite-repair enzymes Nit1 and Nit2
In simple terms: This enzyme belongs to a family of repair enzymes that clean up damaged or unwanted metabolites.
Nit2, the enzyme responsible for 2-oxoglutaramate amidase activity, is related to Nit1, which functions as a metabolite-repair enzyme that hydrolyzes deaminated glutathione. The broader Nit family therefore contributes to metabolite quality control, and the identification of Nit1 function has been described as part of a collaboration that also illuminated omega-amidase biology. This context helps explain why loss of 2-oxoglutaramate amidase activity may have consequences beyond simple nitrogen disposal.
Key Genes Involved in GO:0106008 2-oxoglutaramate amidase activity
The genes and proteins most directly associated with 2-oxoglutaramate amidase activity are NIT2 (omega-amidase) and its pathway partners and family members.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NIT2 (Nit2) | Encodes omega-amidase, the enzyme with 2-oxoglutaramate amidase activity | Putative tumor suppressor; core target for KO, point-mutation and overexpression studies |
| NIT1 (Nit1) | Metabolite-repair enzyme that hydrolyzes deaminated glutathione | Family context for Nit2; comparative studies of metabolite repair |
| GPT (glutamic-pyruvic transaminase) | Glutamine transaminase that generates 2-oxoglutaramate | Upstream pathway partner; coupling studies |
| GGT (glutamine transaminase K) | Glutamine transaminase functionally coupled with omega-amidase | Upstream pathway partner; pathway flux analysis |
| GLS (glutaminase) | Contributes to glutamine metabolism feeding the pathway | Context for glutamine flux studies |
| GOT1/GOT2 | Aspartate transaminases linked to alpha-ketoglutarate metabolism | Metabolic context for alpha-ketoglutarate pools |
| IDH1/IDH2 | Produce alpha-ketoglutarate in central metabolism | Comparative source of 2-oxoglutarate |
| DIO2 | Dioxygenase that uses alpha-ketoglutarate as co-substrate | Downstream readout of 2-oxoglutarate availability |
| TET2 | Alpha-ketoglutarate-dependent dioxygenase | Epigenetic readout of alpha-ketoglutarate levels |
| EGLN1 (PHD2) | Alpha-ketoglutarate-dependent oxygen sensor | Signaling readout of 2-oxoglutarate availability |
| KDM5A | Alpha-ketoglutarate-dependent demethylase | Chromatin readout of alpha-ketoglutarate levels |
| NIT2 orthologs in E. coli expression systems | Recombinant production of human omega-amidase | Source of enzyme for kinetics and biocatalysis |
| Nit2 active-site variants | Define catalytic residues for hydrolysis | Point-mutation models of loss of activity |
| Nit1 catalytic variants | Define deaminated glutathione hydrolysis | Comparative mechanism studies |
| Glutamine transaminase variants | Modulate upstream 2-oxoglutaramate supply | Pathway coupling experiments |
| Alpha-ketoglutaramate standards | Analytical reference for pathway assays | Quantification in cells and biofluids |
How Is 2-oxoglutaramate amidase activity Regulated?
The transaminase-omega-amidase pathway, and therefore 2-oxoglutaramate amidase activity, is regulated by metabolic state and oxidative stress. In endothelial cells, the pathway senses oxidative stress to control glutamine metabolism and alpha-ketoglutarate levels, indicating that flux through omega-amidase is responsive to redox conditions. Because the enzyme is functionally coupled with glutamine transaminases, its effective activity depends on the supply of 2-oxoglutaramate generated by those upstream enzymes. The broader Nit family, including the metabolite-repair enzyme Nit1, adds a quality-control layer that can influence pathway output.
2-oxoglutaramate amidase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NIT2 | Putative tumor suppressor; cancer metabolism | NIT2 knockout and point-mutation cell lines with glutamine/alpha-ketoglutarate profiling |
| NIT2 | Endothelial oxidative stress response | Endothelial cells with NIT2 knockout under oxidative stress |
| NIT1 | Metabolite repair and deaminated glutathione handling | NIT1 knockout cells for comparative metabolite-repair studies |
| Glutamine transaminases | Upstream supply of 2-oxoglutaramate | Transaminase knockout or knockdown with pathway flux measurement |
| Alpha-ketoglutaramate metabolism | Chronic hepatoencephalopathy progression | Patient-derived biofluid metabolite profiling and cell models |
Cancer and tumor suppression
NIT2, the gene encoding omega-amidase, was identified as the putative tumor suppressor responsible for 2-oxoglutaramate amidase activity, linking loss of this enzymatic function to cancer biology. Because the enzyme controls alpha-ketoglutarate levels and glutamine metabolism, its dysfunction may alter metabolic and epigenetic programs relevant to tumor growth. The relationship to the metabolite-repair enzyme Nit1 further suggests that defective metabolite quality control could contribute to disease.
Chronic hepatoencephalopathy and metabolic disease
Alpha-ketoglutarate and alpha-ketoglutaramate levels have been assessed for their indicative significance in the progression of chronic hepatoencephalopathy, indicating that the metabolites connected to this activity are clinically measurable. Because 2-oxoglutaramate is the substrate of GO:0106008, changes in its concentration reflect flux through the transaminase-omega-amidase pathway and may serve as biomarkers. This makes the pathway relevant to hepatic and neurological metabolic dysfunction.
Endothelial oxidative stress and vascular biology
In endothelial cells, the transaminase-omega-amidase pathway senses oxidative stress to control glutamine metabolism and alpha-ketoglutarate levels. This places 2-oxoglutaramate amidase activity within redox-sensitive vascular biology, where alpha-ketoglutarate availability influences signaling and metabolic homeostasis. Dysregulation of this pathway could therefore affect endothelial function under oxidative stress.
Metabolite repair and inborn errors of metabolism
The Nit family includes Nit1, a metabolite-repair enzyme that hydrolyzes deaminated glutathione, and the elucidation of its function has been described alongside omega-amidase biology. Defects in metabolite-repair pathways can allow damaged metabolites to accumulate, and the same conceptual framework applies to 2-oxoglutaramate handling by omega-amidase. This supports the view that GO:0106008 is part of a cellular quality-control system with potential relevance to inherited metabolic disorders.
From 2-oxoglutaramate amidase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of NIT2 abolish 2-oxoglutaramate amidase activity? | NIT2 knockout cell line with kinetic assay |
| Which active-site residues are required for hydrolysis? | Point-mutation knock-in of catalytic residues |
| Can wild-type NIT2 rescue metabolic phenotypes? | Knock-in or overexpression of tagged NIT2 |
| How does the pathway respond to oxidative stress? | Endothelial cells with pathway perturbation under oxidative stress |
| Can the enzyme be used for preparative biocatalysis? | Recombinant expression in E. coli and biocatalytic synthesis |
| Are alpha-ketoglutaramate levels altered in disease? | Metabolite profiling in hepatoencephalopathy models and samples |
How to Study the 2-oxoglutaramate amidase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Kinetic assay | Rate of 2-oxoglutaramate hydrolysis to 2-oxoglutarate and ammonia | Enzyme characterization and inhibitor testing |
| Molecular dynamics simulation | Active-site dynamics and substrate positioning | Mechanistic interpretation of catalysis |
| Metabolite profiling | Alpha-ketoglutarate and alpha-ketoglutaramate levels | Disease progression and pathway flux assessment |
| Stable-isotope tracing | Glutamine-derived carbon and nitrogen flux | Pathway activity in cells |
| Recombinant expression in E. coli | Production of active human omega-amidase | Biochemical and structural studies |
| Preparative biocatalysis | Synthesis of alpha-ketoglutaramate | Generation of substrate standards |
| CRISPR knockout | Loss of NIT2 function | Causal testing of the enzyme in cells |
| CRISPR point mutation | Specific catalytic residue requirement | Structure-function validation |
Kinetic assays for 2-oxoglutaramate amidase activity
Kinetic assays are the primary way to measure GO:0106008 directly. Human Nit2/omega-amidase has been characterized by kinetic assay combined with molecular dynamics simulation to define the catalytic active site and activity. Such assays typically monitor the conversion of 2-oxoglutaramate to 2-oxoglutarate and ammonia and can be applied to recombinant enzyme or cell lysates.
Metabolite profiling of alpha-ketoglutarate and alpha-ketoglutaramate
Because the substrate and product of GO:0106008 are alpha-ketoglutaramate and alpha-ketoglutarate, metabolite profiling is a direct readout of pathway flux. Energy metabolites and the indicative significance of alpha-ketoglutarate and alpha-ketoglutaramate have been assessed in the progression of chronic hepatoencephalopathy, demonstrating the clinical utility of such measurements. These methods can be combined with stable-isotope tracing to follow glutamine-derived nitrogen and carbon.
Recombinant enzyme production and biocatalysis
Recombinant production of human omega-amidase (Nit2) in Escherichia coli enables detailed biochemical study and preparative applications. Preparative biocatalytic synthesis of alpha-ketoglutaramate using this enzyme provides authentic substrate for assays and standards. These approaches are essential for generating the reagents needed to study GO:0106008 rigorously.
Structural and computational analysis of the active site
Structural insights into the catalytic active site of human Nit2/omega-amidase have been obtained using kinetic assays and molecular dynamics simulation. Such analyses identify the residues that position 2-oxoglutaramate and water for hydrolysis and guide the design of point-mutation experiments. Comparative analysis with Nit1, a related metabolite-repair enzyme, further informs mechanism.
How CRISPR Can Be Used to Study GO:0106008 2-oxoglutaramate amidase activity
Knockout
CRISPR knockout of NIT2 is the most direct way to eliminate 2-oxoglutaramate amidase activity in cells and to test its causal role in glutamine metabolism and alpha-ketoglutarate homeostasis. Because NIT2 is a putative tumor suppressor, knockout models can be used to examine metabolic and epigenetic consequences of losing this activity. Knockout of upstream glutamine transaminases can complement these studies by reducing substrate supply.
Point Mutation
Point mutation of active-site residues identified by kinetic and molecular dynamics studies allows precise testing of the catalytic mechanism of GO:0106008. Such models distinguish loss of catalytic activity from loss of protein expression or scaffolding functions. They are particularly useful for validating residues predicted to position 2-oxoglutaramate or water.
Knock-in
Knock-in of tagged or epitope-labeled NIT2 enables localization, interaction and turnover studies while preserving endogenous regulation. Knock-in of disease-associated or catalytically altered variants can model pathway dysfunction in an isogenic background. These models are valuable for linking genotype to metabolite phenotypes.
Overexpression
Overexpression of NIT2 increases 2-oxoglutaramate amidase activity and can be used to test whether enhanced flux alters alpha-ketoglutarate levels and downstream dioxygenase-dependent processes. Recombinant overexpression in E. coli also supports enzyme purification and biocatalytic synthesis of alpha-ketoglutaramate. Overexpression models are therefore useful for both cell biology and biochemistry.
How EDITGENE Supports 2-oxoglutaramate amidase activity Research
Researchers studying 2-oxoglutaramate amidase activity-related genes often need to determine whether a candidate gene is causally involved in the pathway or merely correlated with it. Rigorous causal testing requires well-controlled genetic models, quantitative metabolite readouts and, where relevant, recombinant enzyme reagents. EDITGENE provides the full toolkit needed to move from hypothesis to publication-ready evidence for GO:0106008 and its pathway partners.
Contact EDITGENE today to design your custom CRISPR model for 2-oxoglutaramate amidase activity research.
Frequently Asked Questions About 2-oxoglutaramate amidase activity
What is 2-oxoglutaramate amidase activity?
It is the enzyme activity defined by GO:0106008 that catalyzes the reaction 2-oxoglutaramate + H2O = 2-oxoglutarate + NH3, removing the amide nitrogen from 2-oxoglutaramate.
What is the GO ID for 2-oxoglutaramate amidase activity?
The Gene Ontology identifier is GO:0106008, and the term belongs to the molecular_function ontology.
Which gene encodes 2-oxoglutaramate amidase activity in humans?
The activity is attributed to omega-amidase, encoded by NIT2 (Nit2), which was identified as the enzyme functionally coupled with glutamine transaminases and as a putative tumor suppressor.
What reaction does 2-oxoglutaramate amidase catalyze?
It catalyzes the hydrolysis of 2-oxoglutaramate to 2-oxoglutarate and ammonia, as stated in the QuickGO definition and supported by biochemical studies.
What genes are involved in the transaminase-omega-amidase pathway?
The pathway couples glutamine transaminases, which generate 2-oxoglutaramate, with omega-amidase (NIT2), which hydrolyzes it to 2-oxoglutarate and ammonia.
Why is 2-oxoglutaramate amidase activity important for metabolism?
It regenerates 2-oxoglutarate, a central Krebs-cycle intermediate and dioxygenase co-substrate, while preventing accumulation of 2-oxoglutaramate.
Is NIT2 a tumor suppressor?
NIT2 was identified as the putative tumor suppressor corresponding to omega-amidase, linking 2-oxoglutaramate amidase activity to cancer biology.
How is 2-oxoglutaramate amidase activity measured?
It can be measured by kinetic assays monitoring 2-oxoglutaramate hydrolysis, and pathway flux can be assessed by profiling alpha-ketoglutarate and alpha-ketoglutaramate.
Can 2-oxoglutaramate amidase be produced recombinantly?
Yes, a novel efficient producer of human omega-amidase (Nit2) in Escherichia coli has been developed, enabling biochemical and biocatalytic applications.
What diseases are linked to 2-oxoglutaramate amidase activity?
Altered alpha-ketoglutarate and alpha-ketoglutaramate levels are associated with chronic hepatoencephalopathy progression, and NIT2 is a putative tumor suppressor.
Conclusion
GO:0106008, 2-oxoglutaramate amidase activity, is a well-defined molecular function that completes the transaminase-omega-amidase pathway by hydrolyzing 2-oxoglutaramate to 2-oxoglutarate and ammonia. Its importance spans central carbon metabolism, oxidative-stress sensing in endothelial cells, metabolite repair and tumor suppression, with measurable clinical correlates in chronic hepatoencephalopathy. Because the enzyme can be studied kinetically, structurally and genetically, it is an accessible target for CRISPR-based causal experiments and for biocatalytic applications.
References
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- 3. Epova EY et al.. 2021. A novel efficient producer of human ω-amidase (Nit2) in Escherichia coli.. Anal Biochem 632:114332 PMID: 34391728
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