Thermostable tryptophan synthase ofBacillus stearothermophilus expressed inEscherichia coli

The tryptophan synthase genes trpA and trpB, from a moderate thermophile, B. stearothermophilus, were expressed efficiently in E. coli. The recombinant tryptophan synthase amounted to 22% of the soluble cellular protein, and was purified to homogeneity by three steps. Some enzymatic properties of the recombinant enzyme are compared with those of the mesophilic E. coli tryptophan synthase.