Magnesium replacement by polyamines in higher plant cell-free polyphenylalanine synthesis

The characteristics and specific requirements for the formation of polyphenylalanine from Phe-[¹⁴C] in a barley ribosome cell-free incorporation system were detailed. The polyamines spermine, spermidine and putrescine, and the inorganic cations Ca²⁺, Ba²⁺ and Mn²⁺ demonstrated different capabilities for replacing the Mg²⁺ requirement in the incorporation system. Spermine was extremely efficient in this respect, followed by spermidine; all of the cations tested showed discrete concentration ranges of effectiveness. The data supported the suggestion that, at least to a certain extent, the cation requirement for protein syntheis may be non-specific.