Page last updated: 2024-10-24

tryptophan catabolic process to acetyl-CoA

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of tryptophan into other compounds, including acetyl-CoA. [GOC:go_curators]

Tryptophan catabolism to acetyl-CoA is a complex metabolic pathway that involves multiple enzymatic steps and occurs primarily in the liver. Here's a breakdown of the process:

1. **Tryptophan Degradation to Kynurenine:** The first step involves the enzyme **tryptophan dioxygenase (TDO)** or **indoleamine 2,3-dioxygenase (IDO)**, which catalyzes the oxidation of tryptophan to N-formylkynurenine. This step is regulated by various factors, including nutritional status, hormonal signals, and inflammatory cytokines.

2. **N-Formylkynurenine to Kynurenine:** N-formylkynurenine is then hydrolyzed to kynurenine by **formylkynurenine formamidase**.

3. **Kynurenine Metabolism:** Kynurenine undergoes a series of reactions, leading to the production of various metabolites, including:

- **Kynurenic Acid:** This metabolite is a potent inhibitor of the NMDA receptor, playing a role in neuroprotection and neurotoxicity.
- **3-Hydroxykynurenine:** This metabolite is further metabolized to **3-hydroxyanthranilic acid** (3-HAA).

4. **3-Hydroxyanthranilic Acid (3-HAA) to Quinolinate:** 3-HAA is then converted to **quinolinate**, a precursor for NAD+.

5. **Quinolinate to Nicotinamide Adenine Dinucleotide (NAD+):** Quinolinate is used in the biosynthesis of **NAD+**, a crucial coenzyme involved in numerous metabolic reactions.

6. **Alternative Pathway: Kynurenine to Anthranilate:** A separate pathway exists where kynurenine can be converted to **anthranilate** by **kynureninase**. Anthranilate can then be further metabolized to **picolinate**, a precursor for NAD+.

7. **Acetyl-CoA Production:** The key point to note is that **tryptophan catabolism does not directly produce acetyl-CoA**. Instead, the degradation of tryptophan through the kynurenine pathway yields metabolites that are essential for other metabolic processes, including NAD+ biosynthesis. Acetyl-CoA is generated through other pathways, such as the breakdown of carbohydrates (glycolysis) and fatty acids (beta-oxidation).

In summary, while tryptophan catabolism to acetyl-CoA is not a direct process, it's an essential pathway that contributes to the production of important metabolites like NAD+, which plays a vital role in cellular energy metabolism. The kynurenine pathway also has significant implications for neurotransmission, inflammation, and immune function.'
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Proteins (1)

ProteinDefinitionTaxonomy
Tryptophan 2,3-dioxygenaseA tryptophan 2,3-dioxygenase that is encoded in the genome of human. [PRO:DNx, UniProtKB:P48775]Homo sapiens (human)

Compounds (13)

CompoundDefinitionClassesRoles
tryptophantryptophan : An alpha-amino acid that is alanine bearing an indol-3-yl substituent at position 3.

Tryptophan: An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.
erythrose 4-phosphate/phosphoenolpyruvate family amino acid;
L-alpha-amino acid;
L-alpha-amino acid zwitterion;
proteinogenic amino acid;
tryptophan;
tryptophan zwitterion
antidepressant;
Escherichia coli metabolite;
human metabolite;
micronutrient;
mouse metabolite;
nutraceutical;
plant metabolite;
Saccharomyces cerevisiae metabolite
chaetochrominchaetochromin: from Chaetomium spp.; RN given refers to chaetochromin A
norharmanbeta-carboline : The parent compound of the beta-carbolines, a tricyclic structure comprising an indole ring system ortho- fused to C-3 and C-4 of a pyridine ring.

norharman: RN given refers to parent cpd
beta-carbolines;
mancude organic heterotricyclic parent
fungal metabolite;
marine metabolite
tryptanthrinetryptanthrine: minor constituent of traditional Chinese medicine qing daialkaloid antibiotic;
organic heterotetracyclic compound;
organonitrogen heterocyclic compound
4-(2-thiazolylazo)resorcinol4-(2-thiazolylazo)resorcinol: sensitive indicator for metals
celastrolmonocarboxylic acid;
pentacyclic triterpenoid
anti-inflammatory drug;
antineoplastic agent;
antioxidant;
EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor;
Hsp90 inhibitor;
metabolite
cryptotanshinonecryptotanshinone: from Salvia miltiorrhizaabietane diterpenoidanticoronaviral agent
tanshinone ii atashinone IIA: a cardiovascular agent with antineoplastic activity; isolated from Salvia miltiorrhiza; structure in first sourceabietane diterpenoid
nsc 36398NSC 36398: structure in first source
harmanharman : An indole alkaloid fundamental parent with a structure of 9H-beta-carboline carrying a methyl substituent at C-1. It has been isolated from the bark of Sickingia rubra, Symplocus racemosa, Passiflora incarnata, Peganum harmala, Banisteriopsis caapi and Tribulus terrestris, as well as from tobacco smoke. It is a specific, reversible inhibitor of monoamine oxidase A.

harman: a beta-carboline; RN given refers to parent cpd; structure
harmala alkaloid;
indole alkaloid;
indole alkaloid fundamental parent
anti-HIV agent;
EC 1.4.3.4 (monoamine oxidase) inhibitor;
plant metabolite
680c91680C91 : A fluoroindole that is 6-fluoroindole in which the hydrogen at position 3 has been replaced by a 2-(pyridin-3-yl)vinyl group (trans configuration). It is a selective inhibitor of tryptophan 2,3-dioxygenase (TDO), which directs the conversion of trypophan to kynurenin.fluoroindole;
olefinic compound;
pyridines
EC 1.13.11.11 (tryptophan 2,3-dioxygenase) inhibitor
beta-3-oxindolylalaninebeta-3-oxindolylalanine: main intermediate in tryptophan degration occurring in acid hydrolysis of protein
stf 083010STF 083010: inhibits Ire1 endonuclease; structure in first source