Identification and optimization of the effects of endogenous free amino acids on the translational activity of the wheat germ cell-free system

This study identifies factors that are responsible for unpredictable problems associated with the wheat germ cell-free translation system. It is shown that variable amounts of an inhibitor of radioisotope incorporation are routinely included in wheat germ cell-free system preparations, even though this activity can be readily reduced by discarding the appropriate fractions of the wheat germ extracts. This inhibition of the incorporation of radioactive amino acid appears to be due to the production of large amounts of some amino acids by wheat germ extracts. Since the free amino acids that occur at high concentrations are described, the results of this study allow one to predict and to minimize this problem. The results also indicate that the choice of the radioactive amino acid precursor used for a translation should be based not only on the abundance of the amino acid in the protein that is being made, but also on the concentration of this amino acid in the wheat germ preparation.