Circular dichroism of helical structures using semiempirical methods

2007 ◽  
Vol 127 (20) ◽  
pp. 204101 ◽  
Author(s):  
Edith Botek ◽  
Benoît Champagne
Keyword(s):  
Circular Dichroism ◽  
Semiempirical Methods ◽  
Helical Structures ◽  
Circular Dichroïsm

scholarly journals Inhibition of islet amyloid polypeptide aggregation and associated cytotoxicity by nonsteroidal anti-inflammatory drugs

2016 ◽  
Vol 94 (1) ◽  
pp. 35-48 ◽  
Author(s):  
Jessica S. Fortin ◽  
Marie-Odile Benoit-Biancamano
Keyword(s):  
Circular Dichroism ◽  
Islet Amyloid Polypeptide ◽  
Amyloid Deposition ◽  
Molar Ratio ◽  
Helical Structures ◽  
Islet Amyloid ◽  
Aggregation Inhibitors ◽  
Inflammatory Drugs ◽  
Anti Inflammatory ◽  
Circular Dichroïsm

Nonsteroidal anti-inflammatory drugs (NSAIDs) constitute an important pharmacotherapeutic class that, over the past decade, have expanded in application to a panoply of medical conditions. They have been tested for neurodegenerative diseases such as Alzheimer’s to reduce inflammation and also in the attempt to abrogate amyloid deposition. However, the use of NSAIDs as aggregation inhibitors has not been extensively studied in pancreatic amyloid deposition. Pancreatic amyloidosis involves the misfolding of islet amyloid polypeptide (IAPP) and contributes to the progression of type-2 diabetes in humans and felines. To ascertain their antiamyloidogenic activity, several NSAIDs were tested using fluorometric thioflavin-T assays, circular dichroism, photo-induced cross-linking assays, and cell culture. Celecoxib, diclofenac, indomethacin, meloxicam, niflumic acid, nimesulide, phenylbutazone, piroxicam, sulindac, and tenoxicam reduced fibrillization at a molar ratio of 1:10. The circular dichroism spectra of diclofenac, piroxicam, and sulindac showed characteristic spectral signatures found in predominantly α-helical structures. The oligomerization of human IAPP was abrogated with diclofenac and sulindac at a molar ratio of 1:5. The cytotoxic effects of pre-incubated human IAPP on cultured INS-1 cells were noticeably reduced in the presence of diclofenac, meloxicam, phenylbutazone, sulindac, and tenoxicam at a molar ratio of 1:10. Our results demonstrate that NSAIDs can provide chemical scaffolds to generate new and promising antiamyloidogenic agents that can be used alone or as a coadjuvant therapy.

Structures of plant viruses from vibrational circular dichroism

2005 ◽  
Vol 86 (8) ◽  
pp. 2371-2377 ◽  
Author(s):  
Ganesh Shanmugam ◽  
Prasad L. Polavarapu ◽  
Amy Kendall ◽  
Gerald Stubbs
Keyword(s):  
Circular Dichroism ◽  
Coat Protein ◽  
Mosaic Virus ◽  
Structural Information ◽  
Protein Structures ◽  
Plant Viruses ◽  
Vibrational Circular Dichroism ◽  
Coat Proteins ◽  
Helical Structures ◽  
Circular Dichroïsm

Vibrational circular dichroism (VCD) spectra in the amide I and II regions have been measured for viruses for the first time. VCD spectra were recorded for films prepared from aqueous buffer solutions and also for solutions using D2O buffers at pH 8. Investigations of four filamentous plant viruses, Tobacco mosaic virus (TMV), Papaya mosaic virus, Narcissus mosaic virus (NMV) and Potato virus X (PVX), as well as a deletion mutant of PVX, are described in this paper. The film VCD spectra of the viruses clearly revealed helical structures in the virus coat proteins; the nucleic acid bases present in the single-stranded RNA could also be characterized. In contrast, the solution VCD spectra showed the characteristic VCD bands for α-helical structures in the coat proteins but not for RNA. Both sets of results clearly indicated that the coat protein conformations are dominated by helical structures, in agreement with earlier reports. VCD results also indicated that the coat protein structures in PVX and NMV are similar to each other and somewhat different from that of TMV. The present study demonstrates the feasibility of measuring VCD spectra for viruses and extracting structural information from these spectra.

Synthesis and characterization of a fragment of an ice nucleation protein

1993 ◽  
Vol 71 (5-6) ◽  
pp. 236-240 ◽  
Author(s):  
Paul Ala ◽  
Pele Chong ◽  
Vettai S. Ananthanarayanan ◽  
Neville Chan ◽  
Daniel S. C. Yang
Keyword(s):  
Circular Dichroism ◽  
Synthetic Peptides ◽  
Ph Dependence ◽  
Ice Nucleation ◽  
Helical Structures ◽  
Ice Nucleation Protein ◽  
Helical Content ◽  
The Stability ◽  
Circular Dichroïsm ◽  
Ice Nucleation Proteins

Synthetic peptides were used as models for studying the conformation of ice nucleation proteins. We chemically synthesized four peptides (16-, 24-, 32-, and 48-mer) that consisted of two to six repeats of the consensus repeating octapeptide unit of ice nucleation proteins and evaluated their conformation by circular dichroism spectroscopy. These model peptides exist predominantly as random coils in aqueous solution, but adopt α-helical structures in the presence of trifluoroethanol. The stability of their secondary structures was investigated by monitoring the pH and time dependence of their circular dichroism spectra. Our results indicated that the α-helical content of the 48-mer exhibited a significant pH dependence, while that of the 24- and 32-mer peptides did not. The 32-mer was the only peptide that transformed from the α-helical to a β-sheet structure upon storage. We suggest that the overall conformation of the ice nucleation protein could be a β-sheet.Key words: ice nucleation protein, synthetic peptides, circular dichroism.

Circular dichroism of naphthyltetrahydroisoquinoline alkaloids: calculation of CD spectra by semiempirical methods

Tetrahedron ◽  
1993 ◽  
Vol 49 (16) ◽  
pp. 3305-3312 ◽  
Author(s):  
Gerhard Bringmann ◽  
Klaus-Peter Gulden ◽  
Busse Holger ◽  
Jörg Fleischhauer ◽  
Bernd Kramer ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Semiempirical Methods ◽  
Cd Spectra ◽  
Circular Dichroïsm

Characterization of Tamm-Horsfall Urinary Glycoprotein

1973 ◽  
Vol 31 ◽  
pp. 420-421
Author(s):  
John P. Robinson ◽  
J. David Puett
Keyword(s):  
Electron Microscopy ◽  
Circular Dichroism ◽  
Secondary Structure ◽  
Quaternary Structure ◽  
Normal Adult ◽  
Morphological Properties ◽  
Adult Males ◽  
Circular Dichroïsm ◽  
Urinary Glycoprotein

Much work has been reported on the chemical, physical and morphological properties of urinary Tamm-Horsfall glycoprotein (THG). Although it was once reported that cystic fibrotic (CF) individuals had a defective THG, more recent data indicate that THG and CF-THG are similar if not identical.No studies on the conformational aspects have been reported on this glycoprotein using circular dichroism (CD). We examined the secondary structure of THG and derivatives under various conditions and have correlated these results with quaternary structure using electron microscopy.THG was prepared from normal adult males and CF-THG from a 16-year old CF female by the method of Tamm and Horsfall. CF female by the method of Tamm and Horsfall.

Circular dichroism spectra of adsorbed dye-aggregates

1968 ◽  
Vol 65 ◽  
pp. 146-151 ◽  
Author(s):  
G. Scheibe ◽  
O. Wörz ◽  
F. Haimerl ◽  
W. Seiffert ◽  
J. Winkler
Keyword(s):  
Circular Dichroism ◽  
Circular Dichroism Spectra ◽  
Circular Dichroïsm
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