Physical properties of lipid bilayer membranes: relevance to membrane biological functions.

Abstract

Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) Abbreviations: EPR, electron paramagnetic resonance; PC, phosphatidylcholine; DXPC (where X = L, M, P, S, B, O, E), dilauroyl-, dimyristoyl-, dipalmitoyl-, distearoyl-, dibehenoyl-, dioleoyl-, dielaidoylphosphatidylcholine, respectively; EYPC, egg-yolk phosphatidylcholine; POPC, 1-palmitoyl-2-oleoylphosphatidylcholine; BR, bacteriorhodopsin; IFV, influenza virus; SASL, stearic acid spin label; 16-SASL, 16-doxylstearic acid spin label; SLOT domain, slow oxygen transport domain; DOT method, method of discrimination by oxygen transport; T 1, spin-lattice relaxation time.Here, the word "transport" is used in its basic physical sense indicating the product of the (local) translational diffusion coefficient and the (local) concentration of oxygen in the membrane.

Structural modeling of dual‐affinity purified Pho84 phosphate transporter

“…Site-directed spin label (SDSL) EPR spectroscopy analysis has proven to be a very powerful technology to study structural aspects of all kinds of proteins [27,28] and other biological molecules such as lipids [29,30], DNA [31] and RNA [32] and also in protein-protein [33] and protein-lipid [34] interaction studies. In particular, SDSL-EPR has been widely used for the elucidation of structural aspects of membrane-spanning proteins, which due to their hydrophobic properties are difficult to analyze with conventional crystallographic technologies, (reviewed in [35]).…”

Diadinoxanthin de‐epoxidation as important factor in the short‐term stabilization of diatom photosynthetic membranes exposed to different temperatures

“…Among the pigments, the most important role is played by the carotenoids, which influence the motional freedom of lipid alkyl chains, thereby changing the physical properties of the membranes (Gruszecki & Strzałka, 2005). The carotenoids effect on the membrane properties can be reduced by unsaturation of the lipid alkyl chains (Subczynski, Markowska, Gruszecki, & Sielewiesiuk, 1992;Subczynski, Markowska, & Sielewiesiuk, 1993;Subczynski & Wisniewska, 2000). However, the effect of unsaturation in the hydrophobic membrane interior is rather moderate.…”

Structure and function of biomembranes: influence of nanoparticles

“…Íàòîì³ñòü, ë³ï³äè øâèäêî ì³íÿþòüñÿ ì³ñöÿìè ç ñóñ³äí³ìè ìîëåêóëàìè ó ìåaeàõ îäíîãî ìîíîøàðó (ó ñåðåäíüîìó 10 7 ðàç³â çà ñåêóíäó). Öå º ïðè÷èíîþ øâèäêî¿ ëàòåðàëüíî¿ äèôó糿 ç êîåô³ö³ºíòîì 10 -8 ñì 2 /ñ, ùî ñâ³ä÷èòü ïðî çäàòí³ñòü ìîëåêóëè ïðîñóâàòèñÿ íà â³äñòàíü ó 2 ìêì (äîâaeèíà âåëèêî¿ áàêòåð³àëüíî¿ êë³òèíè) çà 1 ñ. Äîñë³äaeåííÿ òàêîae ïîêàçàëè, ùî ³íäèâ³äóàëüí³ ìîëåêóëè ë³ï³ä³â äóaeå øâèäêî îáåðòàþòüñÿ íàâêîëî ñâ î ñ³ (îáåðòàëüíà äèôóç³ÿ), à ¿õí³ «õâîñòè» çäàòí³ äî çãèíàííÿ [69].…”