Fluorescence-Spectrum Curves of Chlorophylls, Pheophytins, Phycoerythrins, Phycocyanins and Hypericin.

The Antioxidant and Free Radical Scavenging Activities of Chlorophylls and Pheophytins

Chlorophylls are important antioxidants found in foods. We explored the mechanisms through which the a and b forms of chlorophyll and of pheophytin (the Mg-chelated form of chlorophyll) reduce oxidation: we used comet assay to measure prevention of H2O2 DNA damage; we tested for quenching of 1,1-diphenyl-2-picrylhydrazyl (DPPH); we measured the ability to chelate Fe(II); and, we tested their ab...

Quantitative Measurement of Leaf Chlorophylls by Spectrophotometry of Their Pheophytins in Aqueous Alcoholic Extracts.

Electric field effects on the chlorophylls, pheophytins, and beta-carotenes in the reaction center of photosystem II.

We present an electric field modulated absorption spectroscopy (Stark effect) study of isolated photosystem II reaction center complexes, including a preparation in which the inactive pheophytin H(B) was exchanged for 13(1)-deoxo-13(1)-hydroxy-pheophytin. The results reveal that the Stark spectrum of the Q(x) and Q(y) transitions of the pheophytins has a second-derivative line shape, indicating...

Metal-enhanced fluorescence of chlorophylls in single light-harvesting complexes.

Ensemble and single-molecule spectroscopy demonstrates that both emission and absorption of peridinin-chlorophyll-protein photosynthetic antennae can be largely enhanced through plasmonic interactions. We find up to 18-fold increase of the chlorophyll fluorescence for complexes placed near a silver metal layer. This enhancement, which leaves no measurable effects on the protein structure, is ob...

Purification and N-terminal Analyses of Algal Biliproteins.

1. R-, B- and C-phycoerythrins and R- and C-phycocyanins were isolated and purified on a preparative scale by calcium phosphate chromatography, ammonium sulphate fractionation and crystallization. 2. The N-terminal residues of these biliproteins were analysed. Methionine is the only N-terminal residue of all the phycoerythrins, there being about 14 N-terminal residues per molecule of R- and B-p...