Phospholipids chiral at phosphorus. Dramatic effects of phosphorous chirality on the deuterium NMR properties of the choline head group of phospholipids in the liquid crystalline phase

Biochemistry ◽  
1990 ◽  
Vol 29 (49) ◽  
pp. 10912-10918 ◽  
Author(s):  
William M. Loffredo ◽  
Ru Tai Jiang ◽  
Ming Daw Tsai
Keyword(s):  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Phase ◽  
Head Group ◽  
Deuterium Nmr ◽  
Nmr Properties

scholarly journals Conformations, orientations and time scales characterising dimyristoylphosphatidylcholine bilayer membrane. Molecular dynamics simulation studies.

1997 ◽  
Vol 44 (3) ◽  
pp. 607-624 ◽  
Author(s):  
M Pasenkiewicz-Gierula ◽  
T Róg
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Bilayer Membrane ◽  
Liquid Crystalline Phase ◽  
Dynamics Simulation ◽  
Head Group ◽  
Trans Conformation ◽  
Rotational Correlation

The results of molecular dynamics simulation of fully hydrated dimyristoylphosphatidylcholine (DMPC) bilayer membrane in the liquid-crystalline phase are presented. They show that the probability of a gauche conformation varies periodically along the chain with only a slight increase towards the end of the chain. However, the frequency of transition between conformations increases, due to a decrease in the lifetime of the trans conformation, along the chain. The average lifetimes for trans conformations are in the range of 1-2 x 10(-10) s and for gauche conformations in the range of 4-7 x 10(-11) s. The alpha-chain of the DMPC head group has mainly an extended conformation, due to predominantly trans conformation of alpha5 torsion. The rotational correlation time for the P-N vector is 3.7 ns. The C2-C1-O11-P fragment of the DMPC head group (theta1, alpha1, alpha2 torsions) is rigid while the P-O12-C11-C12 fragment (alpha3, alpha4, alpha5 torsions) is flexible. The lateral diffusion coefficient for DMPC self-diffusion in the membrane is 2 x 10(-7) cm2/s; the rate of transverse diffusion is the same. Large differences in the calculated rotational correlation times for the alpha-, beta-, gamma-chains and for the O21-C1 vector indicate that in the liquid-crystalline bilayer each segment of the DMPC molecule exhibits its own rotational freedom, in addition to its internal flexibility resulting from rotational isomerism. The results obtained in these calculations, although in general agreement with some experimental data, shed new light on the dynamical behaviour of phosphatidylcholine molecules in the bilayer membrane in the liquid-crystalline phase.

scholarly journals Electron transfer studies of a conventional redox probe in human sweat and saliva bio-mimicking conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Krishnaveni ◽  
V. Ganesh
Keyword(s):  
Electron Transfer ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Redox Couple ◽  
Liquid Crystalline Phase ◽  
Transfer Reactions ◽  
Redox Probe ◽  
Human Sweat

AbstractModern day hospital treatments aim at developing electrochemical biosensors for early diagnosis of diseases using unconventional human bio-fluids like sweat and saliva by monitoring the electron transfer reactions of target analytes. Such kinds of health care diagnostics primarily avoid the usage of human blood and urine samples. In this context, here we have investigated the electron transfer reaction of a well-known and commonly used redox probe namely, potassium ferro/ferri cyanide by employing artificially simulated bio-mimics of human sweat and saliva as unconventional electrolytes. Typically, electron transfer characteristics of the redox couple, [Fe(CN)6]3−/4− are investigated using electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy. Many different kinetic parameters are determined and compared with the conventional system. In addition, such electron transfer reactions have also been studied using a lyotropic liquid crystalline phase comprising of Triton X-100 and water in which the aqueous phase is replaced with either human sweat or saliva bio-mimics. From these studies, we find out the electron transfer reaction of [Fe(CN)6]3−/4− redox couple is completely diffusion controlled on both Au and Pt disc shaped electrodes in presence of sweat and saliva bio-mimic solutions. Moreover, the reaction is partially blocked by the presence of lyotropic liquid crystalline phase consisting of sweat and saliva bio-mimics indicating the predominant charge transfer controlled process for the redox probe. However, the rate constant values associated with the electron transfer reaction are drastically reduced in presence of liquid crystalline phase. These studies are essentially carried out to assess the effect of sweat and saliva on the electrochemistry of Fe2+/3+ redox couple.

Liquid crystalline phase transitions in hexakis(4-(4′-heptyloxy)biphenoxy)cyclotriphosphazene

1995 ◽  
Vol 18 (5) ◽  
pp. 795-800 ◽  
Author(s):  
K. Moriya ◽  
H. Mizusaki ◽  
M. Kato ◽  
S. Yano ◽  
M. Kajiwara
Keyword(s):  
Phase Transitions ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Phase

scholarly journals Influence of applied electric fields on the positive magneto-LC effects observed in the ferroelectric liquid crystalline phase of a chiral nitroxide radical compound

Soft Matter ◽  
2013 ◽  
Vol 9 (18) ◽  
pp. 4687 ◽  
Author(s):  
Katsuaki Suzuki ◽  
Yoshiaki Uchida ◽  
Rui Tamura ◽  
Yohei Noda ◽  
Naohiko Ikuma ◽  
...  
Keyword(s):  
Electric Fields ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Nitroxide Radical ◽  
Liquid Crystalline Phase
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