WARS, also known as tryptophanyl-tRNA synthetase, belongs to the class I tRNA synthetase family. Two forms of tryptophanyl tRNA synthetase exist, a cytoplasmic form, named WARS, and a mitochondrial form, named WARS2. WARS catalyzes the aminoacylation of tRNA(trp) with tryptophan and is induced by interferon. It also regulates ERK, Akt, and eNOS activation pathways that are associated with angiogenesis, cytoskeletal reorganization and shear stress-responsive gene expression. Recombinant human WARS protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.