Homogeneous preparations of bovine tryptophanyl‐tRNA synthetase (EC 6.1.1.2) contain monosaccharides (mannose, fucose, galactose, N‐acetylglucosamine) as revealed by liquid chromatography. Their content comprises 2.5–3.0% (w/w) of the enzyme composed of two subunits (60 kDa × 2). The same set of sugars was detected in clastase and CNBr‐generated fragments (with molecular masses of approx. 40 kDa and 30 kDa, respectively). It is concluded that bovine tryptophanyl‐tRNA synthetase, in addition to being a metallo‐ and phosphoprotein, is also a glycoprotein.

Bovine tryptophanyl-tRNA synthetase (EC 6.1.1.2) deprived of Zn*+ by chelation with the phosphonate analog of ApIA hydrolized ATP(GTP) to ADP(GDP) although its ability to form tryptophanyl adenylate was impaired. This hydrolytic activity is stimulated by Me and Mn*+ ions and inhibited by Zn *+ . Monoclonal antibody Am1 against the N-terminal domain of the enzyme completely abolished ATP(GTP)ase activity. The core peptide generated after proteolytic splitting of the N-domain lacks this activity. We suggest that the nucleotide binding site(s) different from ATP sites involved in aminoacylation reaction reside(s) at the N-terminal domain(s) of the enzyme.Mammalian aminoacyl-tRNA synthetase; ATPlGTP hydrolysis; Non-canonical enzymatic activity; Zn2' chelation; Ap,A phosphonate analog