page_title: Tyrosine aminotransferase
section_title: Active site
hierarchical_section_title: Tyrosine aminotransferase / Active site
caption_attribution_description: English: Nonpolar side chains holding PLP in place in tyrosine aminotransferase.
context_page_description: Tyrosine aminotransferase is an enzyme present in the liver and catalyzes the conversion of tyrosine to 4-hydroxyphenylpyruvate.
  In humans, the tyrosine aminotransferase protein is encoded by the TAT gene. A deficiency of the enzyme in humans can result in what is known as type II tyrosinemia, wherein there is an abundance of tyrosine as a result of tyrosine failing to undergo an aminotransferase reaction to form 4-hydroxyphenylpyruvate.
context_section_description: Tyrosine Aminotransferase as a dimer has two identical active site.  Lys280 is attached to PLP, which is held in place via two nonpolar amino acid side chains; phenylalanine and isoleucine (see thumbnail on right).  The PLP is also held in place by  hydrogen bonding to surrounding molecules mainly by its phosphate group.
  Shown below is one active site at three different magnifications:
caption: Space filling model depicting non-polar amino acid side chains Phe169 and Ile249.  Notice sandwich effect of the two groups to hold PLP in the correct orientation
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