Catalyzes the formation of 5'adenyl-Trp and tRNA(Trp) but with 5-fold less activity than TrpRS. Increases the solubility of the nitric oxide synthase oxygenase (nos), as well as its affinity for substrate L-arginine and its nitric-oxide synthase activity. The complex between trpS2 and nos catalyzes the regioselective nitration of tryptophan at the 4-position. ATP + L-tryptophan + tRNA(Trp) = AMP + diphosphate + H(+) + L-tryptophanyl-tRNA(Trp) Homodimer. Forms a complex with nos; one homodimer of trpS2 binds one homodimer of nos. The level of expression increases 2.2-fold, 5 hours after exposure to radiation, and returns to near a base line 5 hours later. This protein may not be involved in protein biosynthesis. Belongs to the class-I aminoacyl-tRNA synthetase family.