Purification and Properties of Leucyl-tRNA Synthetase from Bakers' Yeast

Abstract

Abstract Leucyl-tRNA synthetase from bakers' yeast was purified to homogeneity and characterized. The native enzyme has a molecular weight of 120,000 and contains two identical subunits that upon dissociation display very low aminoacylation activity. From the molecular weight and the sedimentation coefficient of the native enzyme (s20,w0 = 6.05 x 10-13) a value of 5.18 x 10-7 was calculated for d20,w0, which leads to a Stokes radius of 40.7 A. For a spherical molecule this radius corresponds to a volume of 282,000 A3. The kinetic parameters for the enzyme with its substrates are typical for this class of enzymes.