A novel UV laser-induced visible blue radiation from protein crystals and aggregates: scattering artifacts or fluorescence transitions of peptide electrons delocalized through hydrogen bonding?

Shukla, Alok Kumar; Mukherjee, Sourav; Sharma, Swati; Agrawal, Vishal; Kishan, K Radha; Guptasarma, Purnananda

doi:10.1016/j.abb.2004.05.007

Cited by 142 publications

(161 citation statements)

References 10 publications

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“…Previously it has been found that β-rich structures could have intrinsic visible fluorescence in both crystal and solution 37, 38 , and in particular this intrinsic visible fluorescence has been demonstrated to gradually develop during the β-rich fibrillar aggregation of amyloid-β (1–40) and (1–42), lysozyme as well as tau 39 . We also found the gradual development of the intrinsic visible fluorescence during the self-assembly of the TDP-43 C-terminal domain (CTD) containing a hydrophobic fragment flanked by two prion-like regions 24 .…”

Section: Resultsmentioning

confidence: 99%

“…Most remarkably this intrinsic visible fluorescence has been characterized to have its origin in the formation of special hydrogen bond networks involved in the backbone C=O and N-H atom groups of peptide bonds, which already have electron delocalization to some degree. The formation of the cross-β fibrillar structures with highly aligned hydrogen bonds will further enhance electron delocalization and thus allow low energy electronic transitions required for the manifestation of this intrinsic visible fluorescence 24, 37–39 .…”

Section: Resultsmentioning

confidence: 99%

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RRM domain of ALS/FTD-causing FUS characteristic of irreversible unfolding spontaneously self-assembles into amyloid fibrils

Lim

Song

2017

Sci Rep

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526-residue FUS functions to self-assemble into reversible droplets/hydrogels, which could be further solidified into pathological fibrils. FUS is intrinsically prone to aggregation, composed of N-terminal low-sequence complexity (LC); RNA-recognition motif (RRM) and C-terminal LC domains. Intriguingly, previous in vivo studies revealed that its RRM is required for manifesting FUS cytotoxicity but the underlying mechanism remains unknown. Here, we characterized solution conformations of FUS and its five differentially dissected fragments, followed by detailed investigations on thermal unfolding, NMR dynamics and self-assembly of RRM. The results decipher: (1) the N- and C-terminal LC domains are intrinsically disordered, while RRM is folded. Intriguingly, well-dispersed HSQC peaks of RRM disappear in the full-length FUS, reminiscent of the previous observation on TDP-43. (2) FUS RRM is characteristic of irreversible unfolding. “Model-free” analysis of NMR relaxation data decodes that RRM has high ps-ns conformational dynamics even over some residues within secondary structure regions. (3) RRM spontaneously self-assembles into amyloid fibrils. Therefore, in addition to the well-established prion-like region, FUS RRM is also prone to self-assembly to form amyloid fibrils. Taken together, FUS RRM appears to play a crucial role in exaggerating the physiological/reversible self-assembly into pathological/irreversible fibrillization, thus contributing to manifestation of FUS cytotoxicity.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

RRM domain of ALS/FTD-causing FUS characteristic of irreversible unfolding spontaneously self-assembles into amyloid fibrils

Lim

Song

2017

Sci Rep

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“…[6–9] This autofluorescence is excited at the edge of the long-wavelength UV range (~ 360–380 nm) and emits in the deep blue (~ 450 nm). Findings in our lab suggested that precursors to this aggregation-associated fluorescence might have already existed prior to protein aggregation.…”

Section: Introductionmentioning

confidence: 99%

Carbonyl-based blue autofluorescence of proteins and amino acids

Niyangoda

Miti

Breydo³

et al. 2017

PLoS ONE

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Intrinsic protein fluorescence is inextricably linked to the near-UV autofluorescence of aromatic amino acids. Here we show that a novel deep-blue autofluorescence (dbAF), previously thought to emerge as a result of protein aggregation, is present at the level of monomeric proteins and even poly- and single amino acids. Just as its aggregation-related counterpart, this autofluorescence does not depend on aromatic residues, can be excited at the long wavelength edge of the UV and emits in the deep blue. Differences in dbAF excitation and emission peaks and intensities from proteins and single amino acids upon changes in solution conditions suggest dbAF’s sensitivity to both the chemical identity and solution environment of amino acids. Autofluorescence comparable to dbAF is emitted by carbonyl-containing organic solvents, but not those lacking the carbonyl group. This implicates the carbonyl double bonds as the likely source for the autofluorescence in all these compounds. Using beta-lactoglobulin and proline, we have measured the molar extinction coefficients and quantum yields for dbAF in the monomeric state. To establish its potential utility in monitoring protein biophysics, we show that dbAF emission undergoes a red-shift comparable in magnitude to tryptophan upon thermal denaturation of lysozyme, and that it is sensitive to quenching by acrylamide. Carbonyl dbAF therefore provides a previously neglected intrinsic optical probe for investigating the structure and dynamics of amino acids, proteins and, by extension, DNA and RNA.

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“…As fluorescence efficiency of ceria is proportional to the percentage of cerium in the Ce ?3 ionization state, the conversion of Ce ?4 to Ce ?3 determines the efficiency of ceria when used as a phosphorous material in solid-state lighting (Zholobak et al 2011). One potential future application for ceria nanoparticles may be in bioimaging as the fluorescent wavelength of ceria is in the visible wavelength range (Shukla et al 2004). Therefore, it is critical to control Ce ?3 ionization states and the corresponded concentration of oxygen vacancies for many applications.…”

Section: Introductionmentioning

confidence: 99%

Control of oxygen vacancies and Ce+3 concentrations in doped ceria nanoparticles via the selection of lanthanide element

et al. 2012

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The effect of lanthanides that have positive association energies with oxygen vacancies, such as samarium and neodymium, and the elements with negative association energies, such as holmium and erbium, on ionization state of cerium and, consequentially, the oxygen vacancy concentration in doped ceria nanoparticles are investigated in this article. Structural and optical characterizations of the doped and undoped ceria nanoparticles, synthesized using chemical precipitation, are carried out using transmission electron microscopy, X-ray diffractometry, optical absorption spectroscopy, and fluorescence spectroscopy. It is deduced that the negative association energy dopants decrease the conversion of Ce ?4 into Ce ?3 and, hence, scavenge the oxygen vacancies, evidenced by the observed increase in the allowed direct bandgap, decrease in the integrated fluorescence intensity, and increased the size of doped nanoparticles. The opposite trends are obtained when the positive association dopants are used. It is concluded that the determining factor as to whether a lanthanide dopant in ceria acts as a generator or scavenger of oxygen vacancies in ceria nanoparticles is the sign of the association energy between the element and the oxygen vacancies. The ability to tailor the ionization state of cerium and the oxygen vacancy concentration in ceria has applications in a broad range of fields, which include catalysis, biomedicine, electronics, and environmental sensing.

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A novel UV laser-induced visible blue radiation from protein crystals and aggregates: scattering artifacts or fluorescence transitions of peptide electrons delocalized through hydrogen bonding?

Cited by 142 publications

References 10 publications

RRM domain of ALS/FTD-causing FUS characteristic of irreversible unfolding spontaneously self-assembles into amyloid fibrils

RRM domain of ALS/FTD-causing FUS characteristic of irreversible unfolding spontaneously self-assembles into amyloid fibrils

Carbonyl-based blue autofluorescence of proteins and amino acids

Control of oxygen vacancies and Ce+3 concentrations in doped ceria nanoparticles via the selection of lanthanide element

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