[Initiation in a polyribosome-dependent protein-synthesizing cell-free system from Saccharomyces (author's transl)]

A method to prepare polyribosomes from yeasts by using the french-press is described. The highest yield of polyribosomes was derived from late log-phase cells. These polyribosomes, incubated in a cell-free system, were able to reinitiate protein synthesis, which was shown by inhibiting aminoacid incorporation by aurintricarboxylic acid, edeine and sodiumfluoride. We developed the translational system in order to look for the optimal ion-conditions of a DNA-dependent protein-synthesizing system. We found out that at the optimal MgCl2-concentration (6 mM) protein synthesis was strongly inhibited by Mangan ions which are required for transcription in yeast. If protein-synthesis was carried out with 2 mM and 3 mM MgCl2 maximal aminoacid incorporation was observed at 2 mM and 1.5 mM MnCl2.