Measuring the Binding of an Antimicrobial Peptide with LPS by Fluoresence Correlation Spectroscopy

2012 ◽  
Author(s):  
Lanlan Yu ◽  
Ling Ding Jeak ◽  
Thorsten Wohland
Keyword(s):  
Antimicrobial Peptides ◽  
Fluorescence Correlation Spectroscopy ◽  
Computational Models ◽  
Correlation Spectroscopy ◽  
New Drugs ◽  
Microbial Diseases ◽  
Fluorescence Correlation ◽  
Β Sheet ◽  
Lipid Interaction

Antimicrobial peptides are an important defense weapon of many organisms, which attack the membrane of bacteria, leading to inhibition of bacterial growth and finally, bacterial death. Despite their ancient origin, it is difficult for bacteria to develop resistance against these peptides. This makes antimicrobial peptides a promising candidate for new drugs against microbial diseases. The target of these peptides is lipopolysaccharides (LPS), which are the major component of the outer membrane of Gram–negative bacteria. Known peptide structures and computational models show an amphipathic cationic pattern BHPHB (B: basic; H: hydrophobic; P: polar residue, respectively), which is the possible binding site of antimicrobial peptides to LPS. A cyclic amphipathic cationic 19–residue peptide (V4) with one disulfide bond has been designed (Frecer et al., unpublished data), which has potential antimicrobial activity. Circular dichroism measurements showed that V4 has a β–sheet structure. The interaction of a fluorophore labeled–V4 with LPS has been investigated by fluorescence correlation spectroscopy (FCS). The study demonstrated that V4 can specifically bind LPS, in contrast to zwitterionic phosphatidylcholine (PC) of eukaryotic cells. FCS makes it possible to study the binding between peptide and LPS at low concentration in vitro. The dissociation constant of the peptide and LPS was obtained using this technique. Key words: antimicrobial peptides, LPS, peptide-lipid interaction, fluorescence correlation spectroscopy

scholarly journals A Comprehensive Review of Fluorescence Correlation Spectroscopy

2021 ◽  
Vol 9 ◽  
Author(s):  
Lan Yu ◽  
Yunze Lei ◽  
Ying Ma ◽  
Min Liu ◽  
Juanjuan Zheng ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Fluorescence Correlation Spectroscopy ◽  
Pair Correlation ◽  
Time Correlation ◽  
Correlation Spectroscopy ◽  
Local Concentration ◽  
Fluorescence Correlation ◽  
Pros And Cons

Fluorescence correlation spectroscopy (FCS) is a powerful technique for quantification of molecular dynamics, and it has been widely applied in diverse fields, e.g., biomedicine, biophysics, and chemistry. By time-correlation of the fluorescence fluctuations induced by molecules diffusing through a focused light, FCS can quantitatively evaluate the concentration, diffusion coefficient, and interaction of the molecules in vitro or in vivo. In this review, the basic principle and implementation of FCS are introduced. Then, the advances of FCS variants are reviewed, covering dual-color FCCS, multi-focus FCS, pair correlation function (pCF), scanning FCS, focus-reduced FCS, SPIM-FCS, and inverse-FCS. Besides, the applications of FCS are demonstrated with the measurement of local concentration, hydrodynamic radius, diffusion coefficient, and the interaction of different molecules. Lastly, a discussion is given by summarizing the pros and cons of different FCS techniques, as well as the outlooks and perspectives of FCS.

scholarly journals Antenna Protein Clustering In Vitro Unveiled by Fluorescence Correlation Spectroscopy

2021 ◽  
Vol 22 (6) ◽  
pp. 2969
Author(s):  
Aurélie Crepin ◽  
Edel Cunill-Semanat ◽  
Eliška Kuthanová Trsková ◽  
Erica Belgio ◽  
Radek Kaňa
Keyword(s):  
Fluorescence Correlation Spectroscopy ◽  
Higher Plants ◽  
Fluorescence Emission ◽  
Correlation Spectroscopy ◽  
Photochemical Quenching ◽  
High Ph ◽  
Fluorescence Correlation ◽  
Non Photochemical Quenching

Antenna protein aggregation is one of the principal mechanisms considered effective in protecting phototrophs against high light damage. Commonly, it is induced, in vitro, by decreasing detergent concentration and pH of a solution of purified antennas; the resulting reduction in fluorescence emission is considered to be representative of non-photochemical quenching in vivo. However, little is known about the actual size and organization of antenna particles formed by this means, and hence the physiological relevance of this experimental approach is questionable. Here, a quasi-single molecule method, fluorescence correlation spectroscopy (FCS), was applied during in vitro quenching of LHCII trimers from higher plants for a parallel estimation of particle size, fluorescence, and antenna cluster homogeneity in a single measurement. FCS revealed that, below detergent critical micelle concentration, low pH promoted the formation of large protein oligomers of sizes up to micrometers, and therefore is apparently incompatible with thylakoid membranes. In contrast, LHCII clusters formed at high pH were smaller and homogenous, and yet still capable of efficient quenching. The results altogether set the physiological validity limits of in vitro quenching experiments. Our data also support the idea that the small, moderately quenching LHCII oligomers found at high pH could be relevant with respect to non-photochemical quenching in vivo.

A fluorescence correlation spectroscopy-based enzyme assay for human Dicer

2012 ◽  
Vol 393 (3) ◽  
pp. 187-193 ◽  
Author(s):  
Arne Werner ◽  
Victor V. Skakun ◽  
Patrick Ziegelmüller ◽  
Ulrich Hahn
Keyword(s):  
Fluorescence Correlation Spectroscopy ◽  
Enzyme Assay ◽  
High Specificity ◽  
Correlation Spectroscopy ◽  
Rnase Activity ◽  
Product Diffusion ◽  
Rnase Iii ◽  
Fluorescence Correlation ◽  
Kinetic Behaviour

Abstract Here, we present an in vitro assay based on fluorescence correlation spectroscopy (FCS), which allows investigation of the kinetic behaviour of human Dicer. The assay is based on the different mobilities of substrate and product. The change of substrate mobility was independent of the choice of the fluorescence label, allowing exclusion of non-specific photophysical artefacts. Dicer and RNase III cleavage led to different product diffusion times. Single-stranded RNA did not change its mobility after cleavage by both double-strand-specific RNases. In agreement with the literature, the RNase activity of Dicer could be inhibited by substituting Ca2+ for Mg2+. In a defined system of two diffusion species of similar label and mobility differences, such as substrate and product, the linearity of the assay could be proven. An FCS-based enzyme assay is proposed, which allows monitoring of Dicer activity with high specificity in vitro.

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