Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 5 de 5
Filter
Add more filters










Database
Language
Publication year range
1.
Langmuir ; 35(37): 12215-12223, 2019 09 17.
Article in English | MEDLINE | ID: mdl-31424219

ABSTRACT

We compare the biophysical and structural aspects of the interaction of amphiphilic ionic liquids containing 1-alkyl-3-methylimidazolium cation ([CnMIM]+, n = 8, 12, or 16) with membranes composed of zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or anionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol (POPG). Liposome affinity and permeabilization were determined using ζ-potential and fluorescence studies, correlated with the cytoxicity of [CnMIM]+Br- toward HeLa cell lines. Membrane affinity is strongest in the case of [C16MIM]+Br- followed by [C12MIM]+Br- and [C8MIM]+Br- for both membranes, and trends remained the same in the case of membrane permeability and cytotoxicity. Solid-state NMR spectroscopy was used to localize [CnMIM]+ inside the lipid bilayers and to study their impact on the head group and acyl chain structures and dynamics of the lipid molecules. The charged ring moiety of the [CnMIM]+ is localized in the lipid-water interface of the membranes irrespective of the chain length and membrane surface charge. While [C8MIM]+ binds the membrane most weakly, it induces the largest disorder in the lipid chain region. A lack of fast flip-flop motions of the amphiphiles in the case of long chain [C16MIM]+ is suggested to render the membrane unstable, which increases its permeability. Between the lipid molecules, the POPC membrane incurs larger disorder in lipid chain packing upon insertion of [CnMIM]+ molecules. The study provides structural details of the impact of increasing chain lengths in [CnMIM]+ on the structural properties of lipid bilayers.


Subject(s)
Cell Membrane/chemistry , Cell Membrane/metabolism , Hydrophobic and Hydrophilic Interactions , Ionic Liquids/chemistry , Ionic Liquids/pharmacology , Alkylation , Cell Membrane/drug effects , Cell Membrane Permeability/drug effects , HeLa Cells , Humans
2.
Proteins ; 87(8): 658-667, 2019 08.
Article in English | MEDLINE | ID: mdl-30958586

ABSTRACT

Structural heterogeneity in the native-state ensemble of dSmt3, the only small ubiquitin-like modifier (SUMO) in Drosophila melanogaster, was investigated and compared with its human homologue SUMO1. Temperature dependence of amide proton's chemical shift was studied to identify amino acids possessing alternative structural conformations in the native state. Effect of small concentration of denaturant (1M urea) on this population was also monitored to assess the ruggedness of near-native energy landscape. Owing to presence of many such amino acids, especially in the ß2 -loop-α region, the native state of dSmt3 seems more flexible in comparison to SUMO1. Information about backbone dynamics in ns-ps timescale was quantified from the measurement of 15 N-relaxation experiments. Furthermore, the noncovalent interaction of dSmt3 and SUMO1 with Daxx12 (Daxx729 DPEEIIVLSDSD740 ), a [V/I]-X-[V/I]-[V/I]-based SUMO interaction motif, was characterized using Bio-layer Interferometery and NMR spectroscopy. Daxx12 fits itself in the groove formed by ß2 -loop-α structural region in both dSmt3 and SUMO1, but the binding is stronger with the former. Flexibility of ß2 -loop-α region in dSmt3 is suspected to assist its interaction with Daxx12. Our results highlight the role of native-state flexibility in assisting noncovalent interactions of SUMO proteins especially in organisms where a single SUMO isoform has to tackle multiple substrates single handedly.


Subject(s)
Drosophila Proteins/chemistry , Drosophila melanogaster/chemistry , Repressor Proteins/chemistry , SUMO-1 Protein/chemistry , Adaptor Proteins, Signal Transducing/chemistry , Adaptor Proteins, Signal Transducing/metabolism , Animals , Drosophila Proteins/metabolism , Drosophila melanogaster/metabolism , Humans , Models, Molecular , Nuclear Magnetic Resonance, Biomolecular , Nuclear Proteins/chemistry , Nuclear Proteins/metabolism , Protein Conformation , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Repressor Proteins/metabolism , SUMO-1 Protein/metabolism , Small Ubiquitin-Related Modifier Proteins
3.
J Phys Chem B ; 122(26): 6763-6770, 2018 07 05.
Article in English | MEDLINE | ID: mdl-29878782

ABSTRACT

The interaction of amphiphilic ionic liquids containing an 1-alkyl-3-methylimidazolium cation ([C12MIM]+), which shows acute cytotoxicity toward marine and bacterial life, with zwitterionic 1-palmitoyl-2-oleoyl- sn-glycero-3-phospho-choline (POPC) and anionic 1-palmitoyl-2-oleoyl- sn-glycero-3-phospho- rac-glycerol (POPG) membranes was investigated. Biophysical parameters of this interaction were quantified by fluorescence spectroscopy, isothermal titration calorimeter, and solution-state NMR measurements. [C12MIM]+ inserts into the membrane and induces vesicle leakage at relatively low concentration (<1 mM). Zwitterionic POPC membranes are more leakage-prone, but the binding of [C12MIM]+ cations is stronger to anionic POPG membranes. A higher rate of exchange of membrane-bound [C12MIM]+ is suspected to play a key role in membrane leakage. Furthermore, solid-state NMR spectroscopy was employed to determine the location of [C12MIM]+ in lipid membranes and its impact on the structure and dynamics of the bilayer. The study provides a molecular understanding of the membrane permeabilizing effect of the [C12MIM]+ mediated by its detergent-like structure.

4.
Mater Sci Eng C Mater Biol Appl ; 72: 590-600, 2017 Mar 01.
Article in English | MEDLINE | ID: mdl-28024626

ABSTRACT

In the pursuit for design of novel bio inspired materials, aromatic α-amino acids (phenylalanine, tyrosine, tryptophan and histidine) have been investigated for the generation of well-ordered self-assembled architects such as fibrils, rods, ribbons and twisted nanosheets in varying solvent systems. These nano/micro scaled architects were thoroughly characterized using FE-SEM, confocal microscopy, optical microscopy, 1H NMR, FTIR, XRD and TGA. These self-assembled architects were histologically stained with Congo red and thioflavin T dyes for investigation of amyloid morphology which revealed that the deposited state of ordered assemblies exhibit specific characteristic of amyloid deposits. The self-assembly of aromatic amino acids was observed to be driven by non-covalent forces such as π-π stacking, van der Waals and electrostatic interaction.


Subject(s)
Amino Acids, Aromatic/chemistry , Amyloid/chemistry , Amino Acids, Aromatic/metabolism , Amyloid/metabolism , Benzothiazoles , Congo Red/chemistry , Congo Red/metabolism , Magnetic Resonance Spectroscopy , Microscopy, Atomic Force , Microscopy, Confocal , Nanostructures/chemistry , Spectroscopy, Fourier Transform Infrared , Thermogravimetry , Thiazoles/chemistry , Thiazoles/metabolism , Water/chemistry , X-Ray Diffraction
5.
Chem Commun (Camb) ; 51(20): 4227-30, 2015 Mar 11.
Article in English | MEDLINE | ID: mdl-25670155

ABSTRACT

Direct disubstitution at the methylene bridges of p-tert-butylcalix[6]arenemethyl ether has been achieved for the first time using a lithiation-substitution protocol. Two stable conformers have been isolated using column chromatography, and their structures have been unambiguously confirmed from 1D, 2D and variable temperature NMR studies and single crystal X-ray structure analysis.

SELECTION OF CITATIONS
SEARCH DETAIL
...