SITE‐SELECTION and SHPOLSKII SPECTROSCOPY OF MODEL PHOTOSYNTHETIC SYSTEMS

Abstract

Abstract— Low temperature (T= 10 K) site‐selection fluorescence and excitation spectra of both isolated pheophorbide‐a molecules (I PHEO) and pheophorbide covalently bonded to the synthetic l‐lysyl‐l‐alanyl‐l.‐alanine polypeptide (B PHEO) were measured in dimethylformamide (DMF) matrices. The fluorescence spectra display sharp vibronic lines at different wavenumbers for different dye laser excitation wavelengths, superimposed on a broad band background. Spectral analysis provides frequencies of normal vibrations (FNV) and site distribution functions (SDF). The FNV and SDF of I PHEO in DMF have been found to show good agreement with other chlorophyll‐like molecules. A covalent binding between the polypeptide and PHEO molecules produces only slight changes in FNV but significant broadenings and shifts to lower energies in SDF. The fluorescence spectra of I PHEO in a typical Shpolskii matrix (n‐octane) were also measured and found to exhibit sharp non‐shifting vibronic lines for all wavelengths and kinds of excitation. A general model explaining both site‐selection and Shpolskii spectroscopy is presented.

Fluorescence line narrowing spectrometric analysis of benzo[a]pyrene-DNA adducts formed by one-electron oxidation

“…Red shifts of 100-200 cm"1 for five DNA adducts relative to the corresponding tetrols have been reported (14). Somewhat pertinent also is the observation that the Sx state of pheophorbide a bound to a long-chain polypeptide is red-shifted ~150 cm"1 relative to that of free pheophorbide a (24). The fact that no red shift in the fluorescence of HRP (compared to that of the model adducts) is observed suggests that the adduct is no longer a part of the polynucleotide chain.…”

Role of Fluorescence Line-Narrowing Spectroscopy and Related Luminescence-Based Techniques in the Elucidation of Mechanisms of Tumor Initiation by Polycyclic Aromatic Hydrocarbons and Estrogens

“…[39][40][41][42][43][44][45][46][47] In the last 20 years G. J. Small and co-workers, 40,[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] and several other groups, 41,42,47,[60][61][62][63][64][65][66][67][68][69][70] demonstrated that FLNS is very valuable in the study of various biomolecules, including those resulting from animal and human exposure to various chemical carcinogens. 55,57,59,[71][72][73][74][75][76][77][78] In particular, it has been...…”

Fluorescence line narrowing: a high-resolution window on DNA and protein damage from chemical carcinogens

“…Figure 15. Comparison of the vibrationally excited FLN spectra (Aex = 356.9 nm, T = 4.2 K) of intact human globin (A) with the synthesized ester ALA-BP (B) (oxygen type adduct).…”

“…One could expect, therefore, that the inhomogeneous line width of a specific DNA-PAH adduct imbedded in a glass should lie in this range. More recently, FLNS has been applied to numerous biomolecules and biological systems: chlorophylls o and b (13)(14)(15) pheophytin a (16,17), protochlorophyll and protopheophytin (18), heme proteins (19), iron-free cytochrome c (20), etiolated leaves (21), and bacteriochlorophyll a and bacteriopheophytin a (22). The closely related line narrowing technique of spectral hole burning (10, [23][24][25] has now been applied to a wider variety of photosynthetic protein-pigment complexes (14,22,(26)(27)(28)(29)(30).…”