The Experts below are selected from a list of 33186 Experts worldwide ranked by ideXlab platform
Anthony L Fink - One of the best experts on this subject based on the ideXlab platform.
-
Is Congo Red an Amyloid-specific Dye?
Journal of Biological Chemistry, 2001Co-Authors: Ritu Khurana, Liza Nielsen, Vladimir N Uversky, Anthony L FinkAbstract:Congo Red (CR) binding, monitoRed by characteristic yellow-green birefringence under crossed polarization has been used as a diagnostic test for the presence of amyloid in tissue sections for several decades. This assay is also widely used for the characterization of in vitro amyloid fibrils. In order to probe the structural specificity of Congo Red binding to amyloid fibrils we have used an induced circular dichroism (CD) assay. Amyloid fibrils from insulin and the variable domain of Ig light chain demonstrate induced CD spectra upon binding to Congo Red. Surprisingly, the native conformations of insulin and Ig light chain also induced Congo Red circular dichroism, but with different spectral shapes than those from fibrils. In fact, a wide variety of native proteins exhibited induced CR circular dichroism indicating that CR bound to representative proteins from different classes of secondary structure such as alpha (citrate synthase), alpha + beta (lysozyme), beta (concavalin A), and parallel beta-helical proteins (pectate lyase). Partially folded intermediates of apomyoglobin induced different Congo Red CD bands than the corresponding native conformation, however, no induced CD bands were observed with unfolded protein. Congo Red was also found to induce oligomerization of native proteins, as demonstrated by covalent cross-linking and small angle x-ray scattering. Our data suggest that Congo Red is sandwiched between two protein molecules causing protein oligomerization. The fact that Congo Red binds to native, partially folded conformations and amyloid fibrils of several proteins shows that it must be used with caution as a diagnostic test for the presence of amyloid fibrils in vitro.
Lynette Cegelski - One of the best experts on this subject based on the ideXlab platform.
-
Congo Red interactions with curli producing e coli and native curli amyloid fibers
PLOS ONE, 2015Co-Authors: Courtney Reichhardt, Amy N Jacobson, Marie C Maher, Jeremy Uang, Oscar A Mccrate, Michael Eckart, Lynette CegelskiAbstract:Microorganisms produce functional amyloids that can be examined and manipulated in vivo and in vitro. Escherichia coli assemble extracellular adhesive amyloid fibers termed curli that mediate adhesion and promote biofilm formation. We have characterized the dye binding properties of the hallmark amyloid dye, Congo Red, with curliated E. coli and with isolated curli fibers. Congo Red binds to curliated whole cells, does not inhibit growth, and can be used to comparatively quantify whole-cell curliation. Using Surface Plasmon Resonance, we measuRed the binding and dissociation kinetics of Congo Red to curli. Furthermore, we determined that the binding of Congo Red to curli is pH-dependent and that histidine residues in the CsgA protein do not influence Congo Red binding. Our results on E. coli strain MC4100, the most commonly employed strain for studies of E. coli amyloid biogenesis, provide a starting point from which to compare the influence of Congo Red binding in other E. coli strains and amyloid-producing organisms.
Ritu Khurana - One of the best experts on this subject based on the ideXlab platform.
-
Is Congo Red an Amyloid-specific Dye?
Journal of Biological Chemistry, 2001Co-Authors: Ritu Khurana, Liza Nielsen, Vladimir N Uversky, Anthony L FinkAbstract:Congo Red (CR) binding, monitoRed by characteristic yellow-green birefringence under crossed polarization has been used as a diagnostic test for the presence of amyloid in tissue sections for several decades. This assay is also widely used for the characterization of in vitro amyloid fibrils. In order to probe the structural specificity of Congo Red binding to amyloid fibrils we have used an induced circular dichroism (CD) assay. Amyloid fibrils from insulin and the variable domain of Ig light chain demonstrate induced CD spectra upon binding to Congo Red. Surprisingly, the native conformations of insulin and Ig light chain also induced Congo Red circular dichroism, but with different spectral shapes than those from fibrils. In fact, a wide variety of native proteins exhibited induced CR circular dichroism indicating that CR bound to representative proteins from different classes of secondary structure such as alpha (citrate synthase), alpha + beta (lysozyme), beta (concavalin A), and parallel beta-helical proteins (pectate lyase). Partially folded intermediates of apomyoglobin induced different Congo Red CD bands than the corresponding native conformation, however, no induced CD bands were observed with unfolded protein. Congo Red was also found to induce oligomerization of native proteins, as demonstrated by covalent cross-linking and small angle x-ray scattering. Our data suggest that Congo Red is sandwiched between two protein molecules causing protein oligomerization. The fact that Congo Red binds to native, partially folded conformations and amyloid fibrils of several proteins shows that it must be used with caution as a diagnostic test for the presence of amyloid fibrils in vitro.
Courtney Reichhardt - One of the best experts on this subject based on the ideXlab platform.
-
Congo Red interactions with curli producing e coli and native curli amyloid fibers
PLOS ONE, 2015Co-Authors: Courtney Reichhardt, Amy N Jacobson, Marie C Maher, Jeremy Uang, Oscar A Mccrate, Michael Eckart, Lynette CegelskiAbstract:Microorganisms produce functional amyloids that can be examined and manipulated in vivo and in vitro. Escherichia coli assemble extracellular adhesive amyloid fibers termed curli that mediate adhesion and promote biofilm formation. We have characterized the dye binding properties of the hallmark amyloid dye, Congo Red, with curliated E. coli and with isolated curli fibers. Congo Red binds to curliated whole cells, does not inhibit growth, and can be used to comparatively quantify whole-cell curliation. Using Surface Plasmon Resonance, we measuRed the binding and dissociation kinetics of Congo Red to curli. Furthermore, we determined that the binding of Congo Red to curli is pH-dependent and that histidine residues in the CsgA protein do not influence Congo Red binding. Our results on E. coli strain MC4100, the most commonly employed strain for studies of E. coli amyloid biogenesis, provide a starting point from which to compare the influence of Congo Red binding in other E. coli strains and amyloid-producing organisms.
Vladimir N Uversky - One of the best experts on this subject based on the ideXlab platform.
-
Is Congo Red an Amyloid-specific Dye?
Journal of Biological Chemistry, 2001Co-Authors: Ritu Khurana, Liza Nielsen, Vladimir N Uversky, Anthony L FinkAbstract:Congo Red (CR) binding, monitoRed by characteristic yellow-green birefringence under crossed polarization has been used as a diagnostic test for the presence of amyloid in tissue sections for several decades. This assay is also widely used for the characterization of in vitro amyloid fibrils. In order to probe the structural specificity of Congo Red binding to amyloid fibrils we have used an induced circular dichroism (CD) assay. Amyloid fibrils from insulin and the variable domain of Ig light chain demonstrate induced CD spectra upon binding to Congo Red. Surprisingly, the native conformations of insulin and Ig light chain also induced Congo Red circular dichroism, but with different spectral shapes than those from fibrils. In fact, a wide variety of native proteins exhibited induced CR circular dichroism indicating that CR bound to representative proteins from different classes of secondary structure such as alpha (citrate synthase), alpha + beta (lysozyme), beta (concavalin A), and parallel beta-helical proteins (pectate lyase). Partially folded intermediates of apomyoglobin induced different Congo Red CD bands than the corresponding native conformation, however, no induced CD bands were observed with unfolded protein. Congo Red was also found to induce oligomerization of native proteins, as demonstrated by covalent cross-linking and small angle x-ray scattering. Our data suggest that Congo Red is sandwiched between two protein molecules causing protein oligomerization. The fact that Congo Red binds to native, partially folded conformations and amyloid fibrils of several proteins shows that it must be used with caution as a diagnostic test for the presence of amyloid fibrils in vitro.