High-pressure NMR studies of model membranes and Kramers turnover on solution

The pressure and anesthetic effects on lineshapes and various relaxation times of phospholipid model membranes DPPC in multilamellar dispersions and in unilamellar vesicles have been investigated by using $\sp{31}$P NMR, $\sp2$H NMR, as well as one and two dimensional $\sp1$H NMR techniques in both the liquid crystalline and various gel phases. The results clearly show that the pressure has an ordering effect on both the headgroup and acyl chain regions. Pressure also induces an interdigitated GelX phase which is formed between the GelI and GelII phases. In the pressure-induced GelX phase, the chain region is packed more closely than in the GelI and GelII phases, while the opposite is found for the headgroup region. The addition of positively charged local anesthetic tetracaine molecules alters the conformation of DPPC headgroup, raises the critical pressure of main phase transition, and induces the formation of the GelX phase. The location of TTC molecules in the bilayer vesicles has been determined by 2D NOESY experiments. In particular, $\sp{31}$P NMR experiments on multilamellar dispersions suggest that the TTC molecules are gradually expelled from the bilayers and completely excluded around 3 kbar, while $\sp1$H NMR experiments on sonicated vesicles indicate that the TTC molecules are not excluded from the bilayers up to 5 kbar. $\sp2$H NMR experiments on selectively chain-deuterated DPPC samples indicate a tighter packing in the central parts of the acyl chains and a conformational change at the C-2 segment of the sn-2 chain. The $\sp2$H spin-lattice and spin-spin relaxation times for various sites of the chains indicate differential mobility along the chains.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Peng, Xiangdong

Contributors dc:contributor

• Jonas, Jiri

• Chemistry, Biochemistry
• Chemistry, Physical

Statement dc:rights

• Copyright 1991 Peng, Xiangdong

Language dc:language

eng

Identifier

AAI9210951
(UMI)AAI9210951

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19538