Effects of cholesterol on the binding of the precursor neurotransmitter tryptophan to zwitterionic membranes
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hdl:2117/191682
Tipus de documentArticle
Data publicació2018-10-28
EditorAmerican Institute of Physics (AIP)
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Abstract
The characterization of the microscopical forces between the essential a-amino-acid tryptophan, pre-
cursor of the neurotransmitter serotonin and of the hormone melatonin, and the basic components of
cell membranes and their environments (phospholipids, cholesterol, ionic species, and water) is of
central importance to elucidate their local structure and dynamics as well as the mechanisms respon-
sible for the access of tryptophan to the interior of the cell. We have performed nanosecond molecular
dynamics simulations of tryptophan embedded in model zwitterionic bilayer membranes made by
di-palmitoyl-phosphatidyl-choline and cholesterol inside aqueous sodium-chloride solution in order
to systematically examine tryptophan-lipid, tryptophan-cholesterol, and tryptophan-water interac-
tions under liquid-crystalline phase conditions. Microscopic properties such as the area per lipid,
lipid thickness, radial distribution functions, hydrogen-bonding lengths, atomic spectral densities,
and self-diffusion coefficients have been evaluated. Our results show that the presence of tryptophan
significantly affects the structure and dynamics of the membrane. Tryptophan spends long periods of
time at the water-membrane interface, and it plays a central role by bridging a few lipids and cholesterol
chains by means of hydrogen-bonds. The computed spectral densities, in excellent agreement with
experimental infrared and Raman data, revealed the participation of each atomic site of tryptophan
to the complete spectrum of the molecule. Tryptophan self-diffusion coefficients have been found to
be in between 10 -7 and 10 -6 cm 2 /s and strongly depending of the concentration of cholesterol in the
system.
CitacióLu, H.; Marti, J. Effects of cholesterol on the binding of the precursor neurotransmitter tryptophan to zwitterionic membranes. "Journal of chemical physics", 28 Octubre 2018, vol. 149, núm. 16, p. 164906-1-164906-10.
ISSN0021-9606
Versió de l'editorhttps://aip.scitation.org/doi/abs/10.1063/1.5029430
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