Decomposition of Protein Tryptophan Fluorescence Spectra into Log-Normal Components. I. Decomposition Algorithms

Abstract

Two algorithms of decomposition of composite protein tryptophan fluorescence spectra were developed based on the possibility that the shape of elementary spectral component could be accurately described by a uniparametric log-normal function. The need for several mathematically different algorithms is dictated by the fact that decomposition of spectra into widely overlapping smooth components is a typical incorrect problem. Only the coincidence of components obtained with various algorithms can guarantee correctness and reliability of results. In this paper we propose the following algorithms of decomposition: (1) the SImple fitting procedure using the root-Mean-Square criterion (SIMS) operating with either individual emission spectra or sets of spectra measured with various quencher concentrations; and (2) the pseudo-graphic analytical procedure using a PHase plane in coordinates of normalized emission intensities at various wavelengths (wavenumbers) and REsolving sets of spectra measured with various Quencher concentrations (PHREQ). The actual experimental noise precludes decomposition of protein spectra into more than three components.

Variation of fluorescence in tissue with temperature

“…The variation in fluorescence quantum yield may be due to multiple tryptophan residues which are present in most proteins [12][13][14][15]. These tryptophan residues contribute to the total emission [12][13][14][15].…”

The protein fluorescence and structural toolkit: Database and programs for the analysis of protein fluorescence and structural data

“…uri.edu/. PFAST contains three modules: (1) FCAT is a fluorescence-correlation analysis tool, which decomposes protein fluorescence spectra to reveal the spectral components of individual tryptophan residues or groups of tryptophan residues located close to each other, and assigns spectral components to one of five previously established spectral-structural classes. (2) SCAT is a structural-correlation analysis tool for the calculation of the structural parameters of the environment of tryptophan residues from the atomic structures of the proteins from the Protein Data Bank (PDB), and for the assignment of tryptophan residues to one of five spectral-structural classes.…”

Non-invasive characterization of structure and morphology of silk fibroin biomaterials using non-linear microscopy

“…Spectral shifts in response to a more polar environment have been observed for chromophores such as tryptophan, and are typically attributed to changes in the relaxation of the molecule because of polar interactions or the formation of hydrogen bound complexes in the excited state [48][49][50]. We expect that similar processes are responsible for the observed red shift in the silk spectra of samples exposed to more highly hydrated environments, depicted schematically in Fig.…”