Methionyl-tRNA synthetase of Escherichia coli. A zinc metalloprotein

Abstract

The native dimeric form of methionyl-tRNA synthetase of Escherichia coli contains two zinc atoms per dimer, one per subunit. The bound zinc is retained upon trypsin modification which yields a monomer with one zinc atom. The enzymatic activity of both the dimeric forms is reversibly inhibited by 1,10-phenanthroline but not by its non-chelating analogues. In addition, the native enzyme binds two Mn2+ per dimer with a binding constant of approx. 70 micron but no binding is observed with the trypsin-modified monomer.