Calorimetric Study of the Poly(A)Poly(U) Complexes with Phosphatidylcholine Liposomes and Mg2+.
Kuvichkin VV, Kuznetsova SM, Emelyanenko VI, Zhdanov RI, Petrov AI
Biophysics (Moscow) (1999)
Category: DNA-membrane interaction ¤ Added: Jun 07, 2002 ¤ Rating: ◊
Abstract¬óBinary and ternary complexes of poly(A)⋅poly(U) with dimyristoyl phosphatidylcholine or dipalmitoyl phosphatidylcholine liposomes prepared in the presence or in the absence of Mg2+ were studied by differential scanning calorimetry. The melting enthalpy values of polynucleotides and the liposome phospholipid bilayer were calculated in complexes and in control. The melting enthalpy value of poly(A)⋅poly(U) in ternary complexes was found to decrease as the concentration of Mg2+ and the lipid/polynucleotide ratio increased. This was accompanied by the splitting of the poly(A)⋅poly(U) melting peak into two or three peaks. It was shown that poly(A)⋅poly(U) is able to interact with liposomes in the absence of Mg2+, the interaction giving rise to changes in the melting enthalpy of the components of the system and insignificant shifts in the melting point temperatures. The results of the calorimetric study and the electron microscopic data are consistent with the model of ternary complexes suggested in the preceding works.