scholarly journals Physical studies on phosphonium phosphatidylcholine. A unique [31P]phosphorus nuclear-magnetic-resonance probe for model and biological membranes

1975 ◽  
Vol 151 (3) ◽  
pp. 555-560 ◽  
Author(s):  
E Sim ◽  
P R Cullis ◽  
R E Richards
Keyword(s):  
Phase Transition ◽  
Nuclear Magnetic Resonance ◽  
Transition Temperature ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Phase Transition Temperature ◽  
Shift Reagent ◽  
Scanning Calorimetry ◽  
Distearoyl Phosphatidylcholine ◽  
Nuclear Magnetic

1. Distearoyl phosphatidylcholine and the phosphonium analogue, in which the nitrogen atom is replaced by phosphorus, show similar gel-liquid crystalline transition temperatures as detected by differential scanning calorimetry. 2. The temperature-dependence of the 31P n.m.r. (nuclear-magnetic-resonance) linewidths of the phosphate resonances of sonicated vesicles of distearoyl phosphatidylcholine and the phosphonium analogue are similar. Below the phase-transition temperature the linewidths decrease as the temperature is raised. Above the phase-transition temperature the phosphate resonances are relatively temperature-independent. The phosphonium 31P n.m.r. signal exhibits the same pattern of temperature-dependence. 3. The 31P n.m.r. phosphonium resonance is sensitive to the paramagnetic shift reagent, K3Fe(CN)6. Use of K3Fe(CN)6, together with Nd(NO3)3, enabled the determination of the trans-bilayer distribution of egg-yolk phosphatidylcholine and its phosphonium analogue in co-sonicated vesicles. Both are distributed comparably across the bilayer of the vesicles. 4. The phosphonium 31P n.m.r. signal is much sharper than the corresponding phosphate resonance in both sonicated and unsonicated dispersions of the phosphatidylcholine analogue. 5. The properties of the phosphonium analogue of phosphatidylcholine are discussed in terms of its suitability as a probe of membrane structure.

Ordering of the O(2)…D… O(2) bonds near the phase transition in KD3(SeO3)2 single crystals by D nuclear magnetic resonance

Open Physics ◽  
2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Ae Lim ◽  
Se-Young Jeong
Keyword(s):  
Phase Transition ◽  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Transition Temperature ◽  
Magnetic Resonance ◽  
Single Crystals ◽  
Phase Transition Temperature ◽  
Experimental Results ◽  
Abrupt Decrease ◽  
Slowing Down

AbstractDeuterium resonance investigations of KD3(SeO3)2 single crystals have been performed near the phase transition temperature T C. There are two types of deuterium bonds in these crystals with different behaviors at this phase transition. Our experimental results show that there are significant changes in the D spinlattice relaxation time T 1 at T C; the abrupt decrease in T 1 near T C can be explained by the critical slowing down of an overdamped soft pseudospin-type deuteron mode. Further, the ordering of the O(2)…D… O(2) bonds is affected by the phase transition, whereas the ordering of the O(1)-D… O(3) bonds is unaffected. The D NMR measurements also show that the D(2) deuteron disordering above T C is dynamic and not static.

Bilayer stabilizing peptides and the inhibition of viral infection: antimeasles activity of carbobenzoxy-Ser-Leu-amide

1987 ◽  
Vol 7 (9) ◽  
pp. 745-749 ◽  
Author(s):  
Richard M. Epand ◽  
Thomas J. Lobl ◽  
H. E. Renis
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Measles Virus ◽  
Cytopathic Effect ◽  
Hexagonal Phase ◽  
Vero Cells ◽  
Time Parameter ◽  
Scanning Calorimetry ◽  
Hplc Retention Time

A number of carbobenzoxy-dipeptide-amides raise the bilayer to hexagonal phase transition temperature of dielaidoylphosphatidylethanolamine (stabilizes the bilayer). The potency of the peptides in stabilizing the bilayer phase is Z-Tyr-Leu-NH2>Z-Gly-Phe-NH2>Z-Ser-Leu-NH2>Z-Gly-Leu-NH2>Z-Gly-Gly-NH2. A linear correlation was found between the respective HPLC retention time parameter k′ for the peptide and the slope of the bilayer stabilization curve determined with model membranes by differential scanning calorimetry. One dipeptide, Z-Ser-Leu-NH2, reduces measles virus cytopathic effect (CPE) in Vero cells. The mechanism by which this peptide reduces the CPE is not known, although some peptides which raise the bilayer to hexagonal phase transition temperature of phospholipids inhibit membrane fusion.

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