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Approaches for Identification and Validation of Antimicrobial Compounds of Plant Origin: A Long Way from the Field to the Market
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Lívia Maria Batista Vilela, Carlos André dos Santos-Silva, Ricardo Salas Roldan-Filho, Pollyanna Michelle da Silva, Marx de Oliveira Lima, José Rafael da Silva Araújo, Wilson Dias de Oliveira, Suyane de Deus e Melo, Madson Allan de Luna Aragão, Thiago Henrique Napoleão, Patrícia Maria Guedes Paiva, Ana Christina Brasileiro-Vidal, Ana Maria Benko-Iseppon
Some techniques allow to infer the secondary structure, such as circular dichroism spectroscopy that identifies changes in the secondary structure when determining the percentage of alpha-helix, beta sheet and turns. X-ray crystallography and nuclear magnetic resonance reveal the tertiary structure and the interaction of the protein with ligands. Fluorimetric methods indicate changes in the hydrophobic environment, while thermodynamic measurements reveal regions of the protein that differ in stability (Nelson and Cox 2014).
The Structure of Pyruvate Carboxylase
Published in D. B. Keech, J. C. Wallace, Pyruvate Carboxylase, 2018
John C. Wallace, Simon B. Easterbrook-Smith
Circular dichroism — Only limited use has been made so far of circular dichroism to study the structure and conformational changes of this enzyme. The data available to date for chicken liver pyruvate carboxylase554 suggest a helix content of approximately 27% and β-pleated sheet of ~7%. The addition of acetyl-CoA and MgATP caused small changes in the near-UV region, but no detectable effects on the far-UV spectrum.
Interaction of The ANTI-CANDIDA Amphotericin B (And Other Polyene Antibiotics) With Lipids
Published in Rajendra Prasad, Mahmoud A. Ghannoum, Lipids of Pathogenic Fungi, 2017
As far as circular dichroism (CD) is concerned, it represents the most interesting spectroscopic method. The fact that CD spectra present positive and negative bands increases the sensitivity to conformational changes in comparison to electronic absorption. Furthermore, it is the instrument of choice to detect the self-association of chiral molecules: self-association gives rise to intense biphasic dichroic signals (or “excitonic doublet”), easily observed. The higher the extinction coefficient of the molecule, the more intense this doublet. As a matter of fact, AmB with an ε reaching 120000 cm-1 mol-1 presents one of the highest excitonic doublet observed (Δε amplitude as high as 1000 cm-1 mol-1, in water).
Self-assembled non-covalent protein-drug nanoparticles: an emerging delivery platform for anti-cancer drugs
Published in Expert Opinion on Drug Delivery, 2020
Islam A. Hassanin, Ahmed O. Elzoghby
Circular dichroism was reported as a characterization method, involved in the study of the changes occur in the secondary structures of the proteins following the formation of nano-assemblies [113]. As previously discussed, the process of fabrication of protein nano-assemblies relies heavily on protein denaturation and disulfide bond reduction, to induce changes in the conformation of the protein, and allow the exposure of hydrophobic binding residues. Therefore, it may be imperative to determine the integrity of the secondary structures of a protein nano-assembly. For instance, it was found that thermal treatment and H2O2 oxidation of free thiols did not induce changes in the secondary structures of ovalbumin nanoparticles, preserving α-helix structures (two characteristic peaks of α-helix were observed at 208 nm and 222 nm, respectively) in the protein [42]. However, disulfide bond reduction may induce conformational changes, and a decrease in the α-helices. Using β- ME, or Cysteine, a decrease in the α-helical structures was induced in the nano-assemblies compared to native protein structure [15,101].
Comparison of cationic liposome and PAMAM dendrimer for delivery of anti-Plk1 siRNA in breast cancer treatment
Published in Pharmaceutical Development and Technology, 2020
Upendra Bulbake, Nagavendra Kommineni, Maksim Ionov, Maria Bryszewska, Wahid Khan
Circular dichroism was employed as analytical technique to study the effects of complexation on the structure/conformation of the nucleic acid (siPlk1). RNAs have a broad positive composite band and a large negative band at 260 nm and 210 nm respectively, which readily characterized by the double-stranded RNA A-form helix (Gray et al. 1981). The ellipticity of lipoplexes and dendriplexes decreased in all samples with the increasing CLs/PG4:siPlk1 charge ratio (Figure 3(A2,B2)). The alteration in θ/θ0 after addition of CLs/PG4 to siPlk1 is shown in Figure 3(A3,B3). This reduction can be explained by the decreased absorbance of nucleic acids in CLs/PG4:siPlk1 complexes (Law et al. 2008). After addition of CLs/PG4 to siPlk1, the lipoplexes and dendriplexes had a red-shift from 260 to 280 nm for the positive peak and from 210 nm to 220 nm for the negative peak. However, the common A-form structure pattern of CD spectra was retained, suggesting that CLs and PG4 does not seriously change the conformation of siPlk1.
The interaction between self – assembling peptides and emodin and the controlled release of emodin from in-situ hydrogel
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Weipeng Wei, Cui Meng, Yuhe Wang, Yongsheng Huang, Wenbin Du, Hongfang Li, Yanfei Liu, Hong Song, Fushan Tang
Circular dichroism is a very important tool for studying the secondary structure of peptides or proteins. The secondary structure of the protein has four common forms: α-helix, β-sheet, β-turn and random curl. The secondary structure with β-sheet generally has a positive absorption peak at 195–197 nm and a negative absorption peak at 217–218 nm. It can be seen from Figure 5 that the peptides, RADA16-I and RVDV16-I, both had a typical β-sheet secondary structure; in the absence of EM, the absorption intensities increased significantly; and the absorption intensity also increased as the concentration of the peptides increased. At the same peptide concentration, the absorption intensity of RVDV16-I was lower than that of RADA16-I, which might be due to the increased surface tension caused by the stronger hydrophobic interaction of RVDV16-I with EM. These results indicated that RADA16-I and RVDV16-I both can interact with EM and the interaction can result in a slight change in the secondary structure of the peptides.