We report the results of x-ray-scattering studies of individual helical ribbons formed in multicomponent solutions of cholesterol solubilized by various surfactants. The solutions were chemically defined lipid concentrate (CDLC) and model bile. In these and many analogous multicomponent surfactant-cholesterol solutions, helical ribbons of two well defined pitch angles, namely 11 degrees and 54 degrees, are formed. We have suggested previously that this remarkable stability results from an underlying crystalline structure of the sterol ribbon strips. Using a synchrotron x-ray source, we have indeed observed Bragg reflections from individual ribbons having 11 degrees pitch angle. We have been able to deduce the parameters of the unit cell. The crystal structure of these ribbons is similar to that of cholesterol monohydrate, with the important difference that the length of the unit cell perpendicular to the cholesterol layers is tripled. We discuss possible origins for this triplication as well as the connection between the crystalline structure and the geometrical form of the helical ribbons.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1887567 | PMC |
| http://dx.doi.org/10.1073/pnas.0702967104 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Experimental and Theoretical Study of Two 3D Difunctional Electrocatalytic Hybrid Vanadate-Containing Metal-Organic Motifs.
Inorg Chem
January 2025
Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024, PR China.
Two novel 3D inorganic-organic hybrids based on [VO]/[VO] clusters, [Cu(bbpy)(VO)]·3HO () and [CuAg(pty)(VO)]·HO () (bbpy = 3,5-bis(1-benzimidazole) pyridine, pty = 4'-(4″-pyridyl)-2,2':6',2″-terpyridine), were isolated in the same POV/Cu/N-heterocycle ligand reaction systems. Hybrids and possess novel three-dimensional bimetallic frameworks derived from [VO]/[VO] clusters and Cu-organic complexes. In , bbpy ligands are grafted by Cu to a grid ribbon 2D sheet, which are connected with benzene-like [VO] to yield a 3D framework.
View Article and Find Full Text PDFGrids designed for tomography: Stereovision transmission electron microscopy makes it easy to determine the winding handedness of helical nanocoils.
Micron
January 2025
Health and Medical Research Institute, Department of Life Science and Biotechnology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central-6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan. Electronic address:
Determining the handedness of helical nanocoils using transmission electron microscopy (TEM) has traditionally been challenging due to the deep depth of field and transmission nature of TEM, complementary techniques are considered necessary and have been practiced such as low angle rotary shadowing, scanning electron microscopy (SEM), or atomic force microscopy (AFM). These methods require customized sample preparation, making direct comparison difficult. Inspired by the need to identify the helical winding direction from TEM images alone, we developed a specialized tomography grid to capture stereo-pair images, enabling stereopsis.
View Article and Find Full Text PDFThe present study demonstrates the significance of the C/N ratio and double helical ribbon (DHR) impeller in the anaerobic co-digestion (AnCo-D) of sugar refining process (SRP) effluent and molasses-based distillery spent wash (DSW) for improved biogas production. Both SRP & DSW were mixed in different percentages to achieve an optimum C/N ratio. Further biomethane potential analysis of mixed feeds with different C/N ratios was performed.
View Article and Find Full Text PDFSeeding Control in Chirality Triggering of Red-Emitting Organic Charge-Transfer Cocrystal Helixes from Achiral Molecules.
ACS Appl Mater Interfaces
January 2025
Beijing Institute of Smart Energy, Beijing 102200, China.
Supramolecular chirality has gained immense attention for great potential, in which the rational engineering strategy facilitates unique helical stacking/assembly, high chiroptical behavior, and prime biomedical activity. In this study, we reported a novel chiral organic donor-acceptor cocrystal based on asymmetrical components of benzo()naphtho(1,2-)thiophene (BNT) and 9-oxo-9H-indeno(1,2-)pyrazine-2,3-dicarbonitrile (DCAF) that exhibited red emission using a simple solution approach. During the self-assembly, a kinetically controlled growth of polar solvent or substrate induction led to the chiral packing and helical morphology twisted by the cooperation of electrostatic potential energy and chirality.
View Article and Find Full Text PDFCrystallographic models of ribbons and ribbon-based J-aggregate nanotubes from the geometry of tube ends.
Phys Chem Chem Phys
November 2024
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, Moscow 199071, Russia.
Self-assembly into tubular structures typically proceeds by helical winding of ribbon intermediates, however, only the central parts of the tubes, that retain no information on the ribbon geometry, have received attention so far. We propose the procedure of establishing the crystal structure of ribbons and ribbon-based tubes on the basis of crystallographic analysis of the tube-end geometry, where the terminal parts of the ribbons fold and form characteristic mono/bilayer polygonal shapes. The terminal parts of flattened J-aggregate nanotubes of trimethine cyanine dye were clearly resolved in electron microscopy and atomic force microscopy images, and the original parallelogram shape of ribbons was reconstructed and interpreted as a two-dimensional [1-10]/[010] facetted crystal with inclined molecular π-stacks parallel to the long ribbon side.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!