ribsomes and soluble enzymes from 12-h cells are more efficient than those from 48-h cells in supporting polyphenylalanine synthesis , and , although the activity of both systems can be stimulated by the addition of e. coli trna , the higher level of incorporation observed in the unstimulated 12-h system ( ribosomes and soluble enzymes ) is maintained .
C0007634
cells
C0035553
ribosomes