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Biochim Biophys Acta. 2014 Mar;1838(3):1031-46. doi: 10.1016/j.bbamem.2013.12.012. Epub 2013 Dec 27.

Insights into the molecular basis of action of the AT1 antagonist losartan using a combined NMR spectroscopy and computational approach.

Author information

1
National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry & Biotechnology, Vas. Constantinou 48, 11635 Athens, Greece. Electronic address: mzervou@eie.gr.
2
Biomedical Research Foundation of the Academy of Athens, 4, Soranou Efesiou, 11527 Athens, Greece.
3
National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry & Biotechnology, Vas. Constantinou 48, 11635 Athens, Greece.
4
Laboratory of Biomolecular Structure, National Institute of Chemistry, Hajdrihova 19, POB 30, SI-1115 Ljubljana, Slovenia; EN-FIST Centre of Excellence, Dunajska 156, SI-1000 Ljubljana, Slovenia.
5
National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry & Biotechnology, Vas. Constantinou 48, 11635 Athens, Greece; Chemistry Department of National Capodistrian University, Zographou, Athens 15784, Greece.

Abstract

The drug:membrane interactions for the antihypertensive AT1 antagonist losartan, the prototype of the sartans class, are studied herein using an integrated approach. The pharmacophore arrangement of the drug was revealed by rotating frame nuclear Overhauser effect spectroscopy (2D ROESY) NMR spectroscopy in three different environments, namely water, dimethyl sulfoxide (DMSO), and sodium dodecyl sulfate (SDS) micellar solutions mimicking conditions of biological transport fluids and membrane lipid bilayers. Drug association with micelles was monitored by diffusion ordered spectroscopy (2D DOSY) and drug:micelle intermolecular interactions were characterized by ROESY spectroscopy. The localisation of the drug in the micellar environment was investigated by introducing 5-doxyl and 16-doxyl stearic acids. The use of spin labels confirmed that losartan resides close to the micelle:water interface with the hydroxymethyl group and the tetrazole heterocyclic aromatic ring facing the polar surface with the potential to interact with SDS charged polar head groups in order to increase amphiphilic interactions. The spontaneous insertion, the diffusion pathway and the conformational features of losartan were monitored by Molecular Dynamics (MD) simulations in a modeled SDS micellar aggregate environment and a long exploratory MD run (580ns) in a phospholipid dipalmitoylphosphatidylcholine (DPPC) bilayer with the AT1 receptor embedded. MD simulations were in excellent agreement with experimental results and further revealed the molecular basis of losartan:membrane interactions in atomic-level detail. This applied integrated approach aims to explore the role of membranes in losartan's pathway towards the AT1 receptor.

KEYWORDS:

Losartan; Molecular dynamics in micelles; Molecular dynamics in phospholipid bilayers with embedded AT(1) receptor; NMR (DOSY, NOESY/ROESY); SDS micelles; Spin labels

PMID:
24374319
DOI:
10.1016/j.bbamem.2013.12.012
[Indexed for MEDLINE]
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