EurekaMag.com logo
+ Translate

Spectra and physical properties of liposomes and mono layers of polymerizable phospho lipids containing di acetylene groups in one or both acyl chains


, : Spectra and physical properties of liposomes and mono layers of polymerizable phospho lipids containing di acetylene groups in one or both acyl chains. Biochemistry 22(13): 3194-3202

Phosphatidylcholine (PC) molecules were synthesized containing a diacetylene group in one (mixed-chain PC) or both acyl chains (identical-chain PC). Upon UV irradiation they form high MW colored polymers. Under identical irradiation conditions the maximum absorption in the visible region of polymerized aqueous dispersions extracted into chloroform-methanol is far greater for mixed-chain PC than for identical-chain PC. Under certain conditions irradiation of identical-chain PC results in polymer which is insoluble in organic solvents. Mixed-chain PC do not form insoluble polymer. The visible spectra of both classes of PC consist of 2 bands which vary with temperature. At all temperatures for identical-chain PC and at temperatures above 9.degree. C for C23 mixed-chain PC and 26.degree. C for C27 mixed-chain PC the thermochromism is fully reversible. When mixed-chain PC are allowed to warm after polymerization at low temperatures, an irreversible shift in the longer wavelength band is observed. This shift is correlated with a change from a sharp positive band in the CD [circular dichroism] of C27 mixed-chain Pc aqueous dispersions at 4.degree. C to a broad negative band at 25.degree. C. The thermochromism may be related to energetic barriers to rearrangement of the polymer crystal lattice. The differences in solubility, visible spectra and thermochromism of polymerized mixed-chain and identical-chain PC favor a model in which short linear segments of polymer are interconnected through the glycerol backbone of the lipid in identical-chain PC while long linear regions are found in mixed-chain PC. The physical properties of polymerizable phosphatidylcholines were examined at the air-water interface and in bulk aqueous dispersions. There is a phase transition in aqueous dispersions of both lipids and in monolayers of identical-chain PC. Monolayers of mixed-chain PC are not stable at low temperature. The phase transition temperatures (Tc) for mixed-chain PC aqueous dispersions are lower than for identical-chain PC with equivalent-length diacetylenic acyl chains. The Tc of polymerizable PC increases with diacetylenic acyl chain length, but not as rapidly as for saturated PC. Above Tc, the order parameter of nitroxide stearic acid spin labels decreases as the nitroxide group is placed closer to the terminal methyl group of the polymerizable PC. The order parameter of spin labels in polymerizable PC is smaller than in saturated PC. Polymerization of the dispersions does not affect the mobility of the spin labels. As expected for liposomes, aqueous dispersions before and after polymerization shrink when exposed to hypertonic solutions of sucrose. Lamellar structures are evident in freeze-fractured and negatively stained liposomes examined under the EM. Liposomes of polymerizable PC are more permeable to glycerol than DMPC [dimyristoylphosphatidylcholine] liposomes above Tc before and after polymerization, although polymerization reduced the permeability. Polymerization markedly enhances the stability of liposomes to precipitation.

(PDF 0-2 workdays service)

Accession: 006459338

PMID: 6309218

Submit PDF Full Text: Here


Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:
Close
Close

Related references

Clejan S.; Bittman R.; Deroo P.W.; Rosenthal A.F., 1978: Permeability properties of liposomes prepared from di acyl phospho lipids di alkoxy phospho lipids di alkyl phospho lipids acylalkoxy phospho lipids with and without cholesterol. Papahadjopoulos, Demetrios (Ed ) Annals Of The New York Academy Of Sciences, Vol 308 Liposomes And Their Uses in Biology And Medicine Conference New York, N Y , Usa, Sept 14-16, 1977 V+462p Illus The New York Academy Of Sciences: New York, N Y , Usa Isbn 0-89072-063-0 441

Leaver J.; Alonso A.; Durrani A.A.; Chapman D., 1983: The physical properties and photo polymerization of di acetylene containing phospho lipid liposomes. The physical properties and photopolymerization of diacetylene-containing phosphatidylcholines with acyl chains of different length and in lipsome form were studied. The structure of these liposomes and their stability during polymerization were e...

Smaby J.M.; Hermetter A.; Schmid P.C.; Paltauf F.; Brockman H.L., 1983: Packing of ether and ester phospho lipids in mono layers evidence for hydrogen bonded water at the sn 1 acyl group of phosphatidyl cholines. To detect any difference in packing due to the functional group at the sn-1(3) position of glycerol, 3 ethanolamine and 3 choline phospholipids were studied in monolayers at the air-water interface. In each series, the chemical linkage at the sn-1...

Kannagi R.; Kino M.; Saito K.; Masuda T., 1982: Phospho lipid acyl chain metabolism during the differentiation of murine leukemia cell lines re distribution of poly unsaturated acyl chains among phospho lipids. Phospholipid acyl chain metabolism was investigated during the differentiation of murine myeloid leukemic cells (M1 cells). Fatty acid composition of the phosphatidylethanolamine (PE) fraction showed no significant change, while a marked decrease...

Roberts M.F.; Dennis E.A., 1978: Chemical shift difference of the alpha methylene groups of the 2 fatty acyl chains of phospho lipids in membrane models. Biophysical Journal 21(3): 122A

Anonymous, 1973: Influence of the polar group on interactions between phospho lipids and sterols in mono layers rapid decomposition of phosphatidyl ethanolamines and cholesterol in mono layers at ph 119

Roberts, M.F.; Bothner-By, A.A.; Dennis, E.A., 1978: Magnetic nonequivalence within the fatty acyl chains of phospho lipids in membrane models proton nmr studies of the alpha methylene groups. The existence of a large chemical shift difference between the .alpha.-methylene groups of the 2 fatty acyl chains of phospholipids in Triton X-100/phospholipid mixed micelles was previously demonstrated using 1H NMR. This difference between the 2...

Brockerhoff H.; Tirri L.; Fong J., 1977: The hydrogen belts of membranes properties of liposomes and mono layers of di acyl di ether and di alkyl phosphatidyl choline and their interaction with cholesterol. Federation Proceedings 36(3): 362

Hayashi M.; Muramatsu T.; Hara I., 1973: Surface properties of synthetic phospho lipids part 2 thermal phase transitions in mono layers. Biochimica et Biophysica Acta 291(2): 335-343

Hayashi M.; Kobayashi T.; Seimiya T., 1981: Interactions between di acyl glycero phospho ethanolamines and n alkanes in mono layers and bi layers. Surface pressure-area isotherms of L-diacylglycerophosphoethanolamines were measured at the n-alkane/water interfaces for alkanes ranging from n-hexane to n-hexadecane. Transition pressures from the expanded film to the condensed state varied larg...