Ad Blocker Detected
Our website is made possible by displaying online advertisements to our visitors. Please consider supporting us by disabling your ad blocker.
Tryptophan aminotransferase is an enzyme that catalyzes the transamination of L-tryptophan. It requires pyridoxal phosphate as a cofactor and an amino group acceptor alpha-ketoglutarate. Tryptophan aminotransferase catalyzes the first step of indole-3-acetic acid (an auxin) biosynthesis and its product is indole-3-pyruvate.
Indole-3-acetic acid is a plant growth hormone that can be synthesized through four major pathways and the indole-3-pyruvate pathway is one of the most common pathways. In indole-3-pyruvate pathway, tryptophan is first converted to indole-3-pyruvate catalyzed by tryptophan aminotransferase and then indole-3-pyruvate is converted to indole-3-acetaldehyde catalyzed by indole-3-pyruvate decarboxylase.
Here, i have mentioned a simple protocol to check the enzyme activity of tryptophan aminotransferase. First, take 1 ml of crude enzyme (pH 7) and supplement it with 10 µmol α-ketoglutarate, 0.03 µmol of pyridoxal phosphate. Start the reaction by adding 10 µmol of L-tryptophan in a total reaction mixture of 1.4 ml.
Now, incubate the reaction mixture for 1 hour at 30 ºC and read the absorbance at 305 nm. The formation of indole-3-pyruvic acid can be analyzed based on the formation of enol form of indole-3-pyruvic acid at neutral pH and the absorbance of 0.17 unit can be correlated with the formation of 1nmol/ml of product (Speedie et al., 1975).