Representative plants containing either the reductive pentose phosphate cycle or the C(4) dicarboxylic acid cycle of photosynthetic carbon dioxide fixation have distinctly different contents of P(700) and chlorophylls a and b. With leaf extracts and isolated chloroplasts from C(4) cycle plants, the mean value of the relative ratio of P(700) to total chlorophyll was 1.83 and the mean value of th...

Accurate quantification of pigments in mixtures is essential in all cases in which separation of pigments by chromatography is impracticable for one reason or another. An example is the analysis of in vivo formation of heavy metal-substituted chlorophylls in heavy metal-stressed plants. We describe here a novel, accurate UV/VIS spectrophotometric method for the quantification of individual chlo...

Chlorophylls have been extensively investigated both experimentally and theoretically owing to the fact that they are essential for photosynthesis. In the reported study, two forms of chlorophyll, chlorophyll a and chlorophyll b, were investigated by means of the density functional theory. Optimization of the S0, S1 and T1 states was performed with the B3-LYP functional. The computed fluorescen...

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...

Introduction Leaf senescence involves degradation of proteins, The activities of chlorophyllase, contents of pigments chlorophylls, nucleic acids, membranes, and subsequent including chlorophyll a and b, chlorophyllide a and b, transport of some of the degradation products to other and phaeophorbide a during leaf senescence under parts of the plant (Buchanan-Wollaston, 1997; Noodén, low oxygen ...

Analyses were made of chlorophyll a and b and fatty acids (18:3, 18:2, 18:1, 18:0, 16:2, 16:1, and 16:0) of greening and senescing leaf tissue. Those dark-grown tissues given a prior treatment of red, far red, or red followed by far red light showed similar increases in chlorophylls and linolenate (18:3) when exposed to continuous white light. In contrast, green barley (Hordeum vulgare L.) leav...

Trimeric (bT) and monomeric (bM) light-harvesting complex II (LHCII) with a chlorophyll a/b ratio of 0.03 were reconstituted from the apoprotein overexpressed in Escherichia coli. Chlorophyll/xanthophyll and chlorophyll/protein ratios of bT complexes and 'native' LHCII are rather similar, namely, 0.28 vs 0. 27 and 10.5 +/- 1.5 vs 12, respectively, indicating the replacement of most chlorophyll ...

A molecular modeling study was conducted on a series of six natural occurring chlorophylls. Quantum chemistry calculated orbital energies were used to estimate frequency of transitions between occupied molecular orbital and unoccupied molecular orbital energy levels of chlorophyll molecules in vivo conditions in standard (ASTMG173) environmental conditions. Obtained results are in good agreemen...

Spectral absorption coefficients of phytoplankton can now be derived, under some assumptions, from hyperspectral ocean color measurements and thus become accessible from space. In this study, multilayer perceptrons have been developed to retrieve information on the pigment composition and size structure of phytoplankton from these absorption spectra. The retrieved variables are the main pigment...