Fluorescence of Cysteine and Cystine

Abstract

We interpret the UV absorption and fluorescence of cysteine and cystine from ab initio calculations of the ground states and lowest excited singlet states of the two molecules. We derive the optimized energies and geometry parameters from HF/6-31G computations on the ground state and CIS/6-31G computations of the excited state. We present vibrational frequencies of the ground and excited states and quantitative predictions for UV absorption and fluorescence. We also show experimental measurements of cystine fluorescence. Cystine is shown to fluoresce at 700 nm.

Interaction of l-Cysteine with ZnO: Structure, Surface Chemistry, and Optical Properties

“…Cystine fluoresces at 700 nm outside of the range of our spectrometer. 47 DL of ZnS in the visible between 500 and 600 nm should be readily observable but is overlapping with the DL of ZnO. We do not observe DL of ZnS at about 450 nm.…”

“…Cysteine itself does not contribute to the PL intensity as cysteine is predicted to absorb at 200 nm and fluoresce at 300 nm. Cystine fluoresces at 700 nm outside of the range of our spectrometer . DL of ZnS in the visible between 500 and 600 nm should be readily observable but is overlapping with the DL of ZnO.…”

Excess Electron Attachment to Disulfide-Bridged l,l-Cystine. An ab Initio Study

“…5,7 Most recently, Hameka et al studied the fluorescence of the neutral cystine by comparing the configuration interaction with single-excitations configuration interaction theoretical results to the results of their experimental measurements of the UV absorption and fluorescence spectra. 8 Even though the number of publications devoted to cysteinecontaining compounds seems large, it is surprising that, to the best of our knowledge, there have been no papers dealing with the possibility of an excess electron binding to cystine published in the literature thus far. The only attempt to study the nondissociative electron capture by the species which mimic the disulfide-bridged cystine containing one S-S bond is that reported by Carles et al and investigating the nondissociative electron capture by a series of saturated disulfides given by the R-S-S-R formula (where R stands for CH 3 , C 2 H 5 , and C 3 H 7 ).…”

“…It has also been shown that protein disulfide radical anions are stable in aqueous solutions, 2 and the reduction of only one disulfide bridge does not have to modify the protein conformation. 3 Cysteine (Cys) as a sulfur-containing amino acid, the cysteine dimer Cys-Cys (involving two cysteine molecules linked with the S-S bond), cystine-containing peptides, and cystine-based cyclic oligoureas have been the subject of experimental and theoretical studies [4][5][6][7][8] recently. In particular, Dahaoui et al studied the electron charge density of L-cystine using X-ray diffraction techniques and concluded that the almost tetrahedral distribution of the valence shell charge concentration of the sulfur atoms suggests sp 3 hybridization.…”

Structural Modeling of Glutathiones Containing Selenium and Tellurium

“…As a result, the reference compounds with the structural data available for comparisons are limited to GSSG [5], cysteine (Chaney & Steinrauf, 1974;Hameka, Jensen, Ong, Samuels & Vlahacos, 1998) and, to some extent, to the simplest chalcogen hydrides H 2 S 2 , H 2 Se 2 and H 2 Te 2 (Boyd, Perkyns & Ramani, 1983;Elemental., 2003). Three structurally similar conformers, one for each chalcogen, were built and oriented in a comparable way.…”