Mn~(2+)和Cu~(2+)与脂质体和脂酶体相互作用的ESR研究

用ESR实验研究了Mn~(2 )、Cu~(2 )与DOPC,DPPC,SPL,DOPA,DPPA脂质体及其与H~ -ATP酶复合体重组的脂酶体的相互作用.通过Mn~(2 )—ESR谱线强度以及Cu~(2 )—ESR谱g因子的测量得出,磷脂分子头部不同的化学组成及其脂酰链的不同状态决定了Mn~(2 )、Cu~(2 )与膜脂结合的强弱程度,通过脂质体和脂酶体中自旋标记物5NS—ESR谱的测量进一步得出Mn~(2 )的结合增大了膜脂排列的序参数,而酶复合体的嵌入都导致与膜脂结合的Mn~(2 )比例减小.因而,当Mn~(2 )与脂酶体相互作用时,膜脂的排列最终达到一个平衡状态.在中性磷脂脂酶体的膜与Mn~(2 )之间,这种相互作用不明显.

ESR STUDY OF THE INTERACTION OF Mn~(2+) Cu~(2+) WITH LIPOSOMES AND PROTEOLIPOSOMES

The interaction between Mn2+, Cu2+ and DOPC, SPL, DOPA, DPPA phos-pholipid liposomes and proteoliposomes incorporating H+-ATPase complex has deen studied by electron paramagnetic resonance spectroscopy. The intensities of characteristic sextet signal of Mn2+-ESR and g-values of Cu2+-ESR spectra was used as the measure of binding strength of Mn2+, Cu2+ to liposomes and proteoliposomes. The result shows that the binding strength of Mn2+, Cu2+ to phospholipids in model membrane is determined both by the polar headgroup and the packing state of the aliphatic chains of phospholipids. The order is DPPA> DOPA>SPL>DPPC>DOPC. The measurements of 5-NS ESR spectra in liposomes and proteoliposomes reveal evidently the interaction between Mn2+ and pho-sphplioids ip model membrane of acidic proteoliposomes and proteoliposomes co-ntainig acidic phospholipids. That is the binding of Mn2+ increases the order parameter S of packing state of aliphatic chains in model membrane. However, the incorporation of H+-ATPase complex results in the changes of the ratio of bound Mn2+ , thereby, when Mn2+ interacts with proteoliposomes, the packing state of aliphatic chains of phospholipids in model membrane reaches an equilibrium state finaly. This kind of interaction is not apparent between proteoliposomes and Mn2+.