- An in vivo effect of the metabolites L-alanine and glycyl-L-leucine on the properties of lysyl-tRNA synthetase from Escherichia coli K-12. I. Influence on subunit composition and molecular weight distribution. Hirshfield, I.N., Yeh, F.M., Zamecnik, P.C. Biochim. Biophys. Acta (1976)