Cofactors

Pyridoxal 5'-phosphate.

Reaction Mechanism

aromatic-amino-acid transaminase By Reference

Tyrosine (aromatic) aminotransferase (TATase) is a well-characterized Fold Type I PLP-dependent enzyme that has natural specificity for the aromatic amino acids tyrosine, phenylalanine, and tryptophan, as well as for the dicarboxylic amino acids aspartate and glutamate.




Transamination occurs in two steps: the amine group of the substrate amino acid residue (the amino donor) undergoes a transaldimination with PLP, liberating Lys and resulting in the oxo-acid product. Then the second substrate accepts the amino group and lysine is reattached to the PLP cofactor in a second transaldinination reaction.

Catalytic Residues

AA	Uniprot	Uniprot Resid	PDB	PDB Resid
Ala	P95468	210	1ay4	210
Asp	P95468	208	1ay4	208
Lys	P95468	243	1ay4	243
Trp	P95468	127	1ay4	127
View Reaction Mechanisms in M-CSA

Reaction Parameters

• Kinetic Parameters

  Organism	KM Value [mM]	Substrate	Comment
  Aspergillus fumigatus	0.4	L-kynurenine	pH 7.4, 25°C, recombinant enzyme, with cosubstrate 2-oxoglutarate
  Paracoccus denitrificans	1.4	L-cysteine	at pH 7.4 and 30°C

• Temperature

  Organism	Temperature Range	Comment
  Pyrococcus furiosus	30 - 95	extremely thermostable aromatic aminotransferase from hyperthermophilic archaeon, very low activity at 30°C, approx. 50% of maximal activity at 65°C
  Thermococcus litoralis	30 - 105	virtually inactive at 30°C, approx. 50% of maximal ArAT-I activity at 70°C, approx. 50% of ArAT-II activity at 80°C, isoenzymes ArAT-I and II
  Bacillus sp. (in: Bacteria)	37 - 80	37°C: about 35% of maximal activity, 50°C: about 90% of maximal activity, 80°C: about 50% of maximal activity

• pH

  Organism	pH Range	Comment
  Azospirillum brasilense	5 - 10	50% of maximal activity at pH 6.0 and pH 9.5
  Klebsiella aerogenes	6 - 9.6	approx. 50% of maximal activity at pH 6.0 and pH 9.6
  Escherichia coli	6 - 9.5	approx. 45% of maximal activity at pH 6.0,: approx. 60% of maximal activity at pH 9.5, phenylalanine
  Flavobacterium sp.	6 - 10	approx. 50% of maximal activity at pH 6.0
  Brevibacterium linens	6.5 - 10	approx. 45% of maximal activity at pH 6.5, approx. 50% of maximal activity at pH 10

Associated Proteins

Citations

• Flavor Formation in Dry-Cured Fish: Regulation by Microbial Communities and Endogenous Enzymes.
• Deletion of the Saccharomyces cerevisiae ARO8 gene, encoding an aromatic amino acid transaminase, enhances phenylethanol production from glucose.
• Effects of six commercially available koji (Chinese Xiaoqu) on the production of ethyl acetate, ethyl lactate, and higher alcohols in Chinese Baijiu (distilled spirit) brewing.
• Mechanism of D-Cycloserine Inhibition of D-Amino Acid Transaminase from Haliscomenobacter hydrossis.
• Cost-effective selective deuteration of aromatic amino acid residues produces long-lived solution ¹H NMR magnetization in proteins.
• [Semi-rational evolution of ω-transaminase from Aspergillus terreus for enhancing the thermostability].
• Comprehensive analysis of metabolites produced by co-cultivation of Bifidobacterium breve MCC1274 with human iPS-derived intestinal epithelial cells.
• A transaminase with β-activity from Variovorax boronicumulans for the production of enantiopure β-amino acids.
• Amino Acid Catabolism: An Overlooked Area of Metabolism.
• The Dynamic Change in Aromatic Compounds and Their Relationship with CsAAAT Genes during the Post-Harvest Process of Oolong Tea.
• Preliminary Study on the Association of Serum Branched-Chain Amino Acids With Lipid and Hepatic Markers.