Peculiarities of the DNA hybridization on the surface of bilayer lipid membranes

The method of electrostriction was applied to study the peculiarities of interaction of short oligonucleotides with free standing (BLM) and supported lipid membranes (sBLM) and of the duplex formation between complementary oligonucleotides on a membrane surface. The 15-mer single stranded DNA (pentadecathymidylate-(dT)(15)) was modified either with cholesterol (CH(dT)(15)) or by palmitoyl chain (C16(dT)(15)). The interaction of CH(dT)(15) with free standing BLM or with BLM formed on an agar or gold support was accompanied by sharp increase of elasticity modulus in direction perpendicular to the membrane plane ,E( perpendicular), and by increase of surface potential. In contrast, C16(dT)(15) did not induce substantial changes of elasticity modulus, however, the surface potential was changed in a similar manner as for CH(dT)(15). Hybridization of DNA following addition of complementary chain (dA)(15) has been accompanied by a small decrease of elasticity modulus and by a slight increase of surface potential. Both the incorporation of chemically modified oligonucleotides into the lipid bilayer as well as hybridization of DNA are not cooperative processes as has been demonstrated by analysis using Scatchard plot of corresponding values.