(or tyrosine transaminase
) is an enzyme present in the liver and catalyzes the conversion of tyrosine
. 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.
Structures of the three main molecules involved in chemical reaction catalyzed by the tyrosine aminotransferase enzyme are shown below: the amino acid tyrosine
, the prosthetic group pyridoxal phosphate
, and the resulting product 4-hydroxyphenylpyruvate
Each side of the dimer protein includes pyridoxal pyruvate (PLP) bonded to the Lys280
residue of the tyrosine aminotransferase molecule. The amine group of tyrosine attacks the alpha carbon of the imine bonded to Lys280, forming a tetrahedral complex and then kicking off the LYS-ENZ. This process is known as transimination by the act of switching out the imine group bonded to PLP. The newly formed PLP-TYR molecule is then attacked by a base.
A possible candidate for the base in the mechanism could be Lys280 that was just pushed off of PLP, which sequesters the newly formed amino group of the PLP-TYR molecule. In a similar mechanism of aspartate......