Tyrosine aminotransferase from Drosophila hydei salivary glands: Characterization, purification, and antibody production

Abstract

Tyrosine aminotransferase (TAT) is an inducible enzyme in Drosophila hydei. This enzyme is characterized by a sharp pH optimum of 6.8. K m values of 4.97 × 10 −5 M, 1.07 × 10 −4 M and 6.01 × 10 −6 M were obtained for tyrosine, α-ketoglutarate and pyridoxine respectively. There was substrate inhibition with high concentrations of α-ketoglutarate. The enzyme was purified from salivary glands by a series of chromatographic steps. The purified enzyme showed a single protein band on both native and SDS polyacrylamide gels. The enzyme activity co-migrated with the single protein band on the native gels. Antibody prepared against the purified protein induced a single precipitin line in Ouchterlony double diffusion gels using either whole larva homogenates or purified TAT as antigen.