Influence of polypeptide molecular and side chain lengths and of side chain steric location on the kinetics of basic polypeptide-induced sensitization of primate cells to transfection.

Kinetics of sensitization of chimpanzee cell sheets to transfection by poliovirus RNA was determined for 5 basic polypeptides. With basic olypeptide hydrobromide at 100 microng/ml, initial sensitization rate was faster for poly-L-ornithine of average molecular weight (AMW) 15500 than of AMW 105000, and much faster for poly-L-lysine of AMW 1700 than of AMW 140000. Desensitization phases were observed with the 2 shorter polypeptides. Sensitization was much faster and sensitivity maxima were considerably higher for the polyornithines than for the polylysines. Poly-D-lysine of AMW 160000 sensitized cells slightly faster than poly-L-lysine of AMW 140000, but gave about the same sensitivity maximum. Analysis of the slow cell sensitization by poly-L-lysine of AMW 140000 revealed 2 steps: a fast step 1 (attachment) and a slow step 2 (processing).