INFLUENCE OF POLYPEPTIDES AND PROTEINS ON ELECTROFUSION OF HUMAN CANCER CELLS

Abstract

The electrofusion of human cancer U937 and K562 cells was studied under the influence of a selected group of polypeptides and proteins adsorbed at their membranes. For poly-L-lysine, we found that the higher the molecular mass (M_m) the higher the relative fusion yield (F_r), whereas poly-L-arginine and poly-L-ornithine showed toxicity. As recently measured for barley protoplast fusion, the same rule of dependence on the isoelectric point (pI) could be verified:which means 0.5 < F_r < 4 in 0.3 M mannitol solution (pH 6). If the pH of the 0.3 M mannitol solution is the same as the pI of the protein, its influence on the membrane nearly disappears. Bridging by Ca ions increases F_r from 0.5 (bovine serum albumin) to F_r ∼ 1 by charge compensation. The value of F_r is commensurate with the pore resealing time τ—determined by trypan blue staining—in such a way that for pI > 8, τ is longer and for pI < 6, τ is shorter than the control without protein content. Qualitatively, plant and animal membranes studied show equal behavior. According to our technique, the adsorption of biopolymers and other substances can be detected by this bioelectrochemical method, which is also a tool for analysis of electric stress mechanisms.