Limited proteolysis of tryptophanyl-tRNA synthetase from beef pancreas.
Treatment of purified tryptophanyl-tRNA synthetase with either chymotrypsin, papain, subtilisin or elastase converts all the enzyme into a high-molecular-weight intermediate. This protease-resistant core molecule has the same dimeric structure as the native protein and possesses the ability to bind substrates (tryptophan, ATP and tRNATrp) but is catalytically inactive. The monomer molecular weight of the protease-treated enzyme is 39000 compared to 54000 for the intact molecule. Chemical studies indicate that proteases excise the amino-terminal part of the polypeptide chain. It has been demonstrated previously that removal of a 13000-dalton fragment from the amino-terminal region of the tryptophanyl-tRNA synthetase converts the native enzyme to another active form. Cleavage of 20 additional amino acids produces the inactive protease-resistant core.
D000596:Amino Acids / Q000032:analysis; D000604:Amino Acyl-tRNA Synthetases / Q000032:analysis*; D000818:Animals; D002417:Cattle; D002918:Chymotrypsin; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010179:Pancreas / Q000201:enzymology*; D010196:Pancreatic Elastase; D010206:Papain; D010446:Peptide Fragments / Q000032:analysis; D013381:Subtilisins; D014369:Tryptophan-tRNA Ligase / Q000032:analysis* / Q000378:metabolism
D000596:Amino Acids; D046911:Macromolecular Substances; D010446:Peptide Fragments; D013381:Subtilisins; D002918:Chymotrypsin; D010196:Pancreatic Elastase; D010206:Papain; D000604:Amino Acyl-tRNA Synthetases; D014369:Tryptophan-tRNA Ligase