Biophysical and biochemical characterization of the intrinsic fluorescence from neurofibrillary tangles

Guoying Bing, Xuan V. Nguyen, Mei Liu, William R. Markesbery, Anyang Sun

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Recently, we developed a novel fluorescent method named intrinsic fluorescence induction that allows direct visualization of neurofibrillary pathology without introducing exogenous chromogens. In the present study, we further characterized the properties of this novel red fluorescence biophysically, biochemically, and neuropathologically. In vitro spectrofluorometry and in situ emission scan show that the intrinsic fluorescence of neurofibrillary tangles has a long emission wavelength peak at 620 nm and a large Stoke's shift of 70 nm. Dephosphorylation of Alzheimer's disease brain sections with alkaline phosphatase or denaturation with guanidine only causes a subtle reduction in the induced fluorescence of neurofibrillary tangles, while hydrofluoric acid or formic acid completely eliminates the fluorescence. Chemical modification of residue serine, but not tyrosine or tryptophan, reduced the intensity of induced fluorescence significantly. The induced fluorophore, thus, has unique properties, and its generation likely depends on the particular conformation of paired helical filaments, which may in turn depend on tau hyperphosphorylation.

Original languageEnglish
Pages (from-to)823-830
Number of pages8
JournalNeurobiology of Aging
Issue number6
StatePublished - Jun 2006

Bibliographical note

Funding Information:
This work was supported by NIH Grants (NS39345) and 5P50AG05144 (WRM). We gratefully acknowledge Drs. Peter Davies and Leonidas G. Bachas for their kind support of this study.


  • Conformation
  • Fluorescence
  • Neurofibrillary tangles
  • Phosphorylation
  • Tau

ASJC Scopus subject areas

  • General Neuroscience
  • Aging
  • Clinical Neurology
  • Developmental Biology
  • Geriatrics and Gerontology


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