Chlorophyll chlorophyll

The equations (1 through 3 below) of the official method for total chlorophyll, chlorophyll a, and chlorophyll b analysis of plants published as Method 942.04 by... 

In plants, the photosynthesis reaction takes place in specialized organelles termed chloroplasts. The chloroplasts are bounded in a two-membrane envelope with an additional third internal membrane called thylakoid membrane. This thylakoid membrane is a highly folded structure, which encloses a distinct compartment called thylakoid lumen. The chlorophyll found in chloroplasts is bound to the protein in the thylakoid membrane. The major photosensitive molecules in plants are the chlorophylls chlorophyll a and chlorophyll b. They are coupled through electron transfer chains to other molecules that act as electron carriers. Structures of chlorophyll a, chlorophyll b, and pheophytin a are shown in Figure 7.9. 

This method gives a bright fluorescence of callose but also a side effect due to the presence of chlorophyll. Chlorophyll dispersed in the specimen yields a red fluorescence all around the tissue, especially a red layer on the surface of the organs due to chlorophyll deposition in any lipid substances, such as a cuticle. 

Figure 23-17 The zigzag scheme (Z scheme) for a two-quantum per electron photoreduction system of chloroplasts. Abbreviations are P680 and P700, reaction center chlorophylls Ph, pheophytin acceptor of electrons from PSII QA, Qg, quinones bound to reaction center proteins PQ, plastoquinone (mobile pool) Cyt, cytochromes PC, plastocyanin A0 and Aj, early electron acceptors for PSI, possibly chlorophyll and quinone, respectively Fx, Fe2S2 center bound to reaction center proteins FA, FB, Fe4S4 centers Fd, soluble ferredoxin and DCMU, dichlorophenyldimethylurea. Note that the positions of P682, P700, Ph, Qa/ Qb/ Ay and A, on the E° scale are uncertain. The E° values for P682 and P700 should be for the (chlorophyll / chlorophyll cation radical) pair in the reaction center environment. These may be lower than are shown.

Eubacteria Eubacteria Archeobacteria Anoxygenation Oxygenation Halogen arion Bacterial chlorophyll Chlorophylls Bacterial rhodopsin Hj, HoS. S. Oiganics H20,H2S Do not participate ATP + NO, D, P(H) ATP + NO, D. P(H1 ATP CO2 + Organics CO2 + Organics Organics... 

D. Application HPLC Analysis of Chlorophylls, Chlorophyll Derivatives, and Carotenoids in Spinach (Ref. 99)... 

Fig. 11 Chromatogram of chlorophylls, chlorophyll derivatives, and carotenoids extracted from spinach leaves and analyzed by HPLC with a photodiode array detector. Chd = chlorophyllide, Pb = pheophorbide, Chi = chlorophyll, Po = pheophytin. (From Ref. 99.)...

Many of the effects that occur as a result of these fumigations can probably be attributed to a destruction of chlorophyll. Chlorophyll loss attributed to fumigation with ozone or ozonated hexenes has been described (37, 39, 40, 41) and can be used as a quantitative measure of injury to cultured plants by certain pollutants. However, in the case of N02, growth suppression of tomato and bean occur after exposure to 0.5 ppm N02 for 10-12 days with a concomitant greening of the leaves, indicating the possibility of nitrogen accumulation and no chlorophyll destruction by the pollutant. 

Chlorophylls chlorophylls have a variety of functions in photosynthetic systems, including collection of photons, transfer of excitation energy, operation of the primary photoinduced charge separation, and transfer of the resulting photoelectrons. Resonance Raman spectroscopy offers the possibility of selectively observing chlorophylls in their native structures (Lutz, 1984 Koyama et al., 1986 Tasumi and Fujiwara, 1987 Lutz and Robert, 1988 Nozawa et al., 1990 Lutz and Mantele, 1991). Transient Raman spectroscopy is a unique method of revealing the excited state structures of chlorophylls. The T1 and SI states were revealed by nanosecond Raman spectroscopy (Nishizawa et al., 1989 Nishizawa et al., 1991 Nishizawa and Koyama, 1991). 

A dimeric nature of P-700 was first proposed to explain its long wavelength of absorption and its circular dichroism spectrum, which can be attributed to chlorophyll-chlorophyll exciton interaction [15]. When two chlorophylls are close together, excitation by light tends to promote electronic transitions which belong to the pair and not to the individual molecules. In particular for the Qy transition, instead of one transition at the frequency v, an excitonic interaction will create two transitions at v +dv and v-dv. The latter is considered to be the transition at 700 nm, whereas the former could be of low intensity. 

Chlorophyll. The AOAC spectrophotometric method ( 9) was used for determination of chlorophyll. A Perkin-Elmer model Coleman 575 spectrophotometer was used to measure the absorbance at 660 and 642.5 nm respectively. The results were reported as chlorophyll, chlorophyll a and chlorophyll b. 

Chlorophylls. Chlorophyll pigments are responsible for the greenish hues in virgin olive oil. Their content may range from 10 to 30 mg/kg. The main chlorophyll present in packed oil is pheophytin a. Chlorophyll a occurs in the oil just after production. Minguez-Mosquera and co-workers (1990) reported the presence of chlorophyll a, chlorophyll b, pheophytin a and pheophytin b in fresh oils. Psomiadou and Tsimidou (2001) found no chlorophyll a and only... 

C.l. 1966 Chlorofolin Chlorofyl Chlorophyll Chlorophylls Deodophyll E 140 EINECS 215-800-7 L-Gruen No. 1 L-Grun No, 1, The green pigments of plants and green algae contain chlorophyl... 

See also Chlorophyll, Chlorophyll b, Protoporphyrin IX, Figure 17.8, / -Carotene, Chloroplasts... 

See also Light Absorbing Pigments, Chloroplast Anatomy, Photosystem II, Photosystem I, The Chloroplast, Chlorophyll, Chlorophyll a, Chlorophyll b... 

May, Paul. Chlorophyll. School of Chemistry, University of Bristol. http //www.chm.bris.ac.uk/motm/chlorophyll/chlorophyll h. htm (accessed on October 3, 2005). 

Gyanobacteiia were apparently the first organisms that developed the ability to use water as the ultimate reducing agent in photosynthesis. As we have seen, this feat required the development of a second photosystem as well as a new variety of chlorophyll, chlorophyll a rather than bacteiiochlorophyll in this case. Ghlorophyll b had not yet appeared on the scene, as it occurs only in eukaryotes. The basic system of aerobic photosynthesis was in place with cyanobacteria. As a result of aerobic photosynthesis by cyanobacteria, the Earth... 

Chlorophylls Chlorophylls Chloroplasts Algae Reaction centers Tetrapyrrole Selectively obtain RR spectra of e.g. chlorophyll a and b in situ. Nature of binding site in protein. Mg coordination number... 

The fluorescence quantum yield of monomeric chlorophyll-a in solution hardly varies with solvent [10], and a value of 0.32 was used for the fluorescence quantum yield of the uncoupled chlorophyll. Chlorophyll-a in ether exhibits a lifetime of 6.7 ns, which is similar to the lifetime of the uncoupled chlorophyll, which is assumed to be in a protein environment. This suggests that chlorophyll monomers in these different environments will have similar fluorescence quantum yields. 

Isaksen (1991) provided an extensive review on the TLC of natural pigments. He stated that TLC is the most common method used to analyze natural pigments. Pigments considered by Isaksen include the flavonoids, anthocyanins, carotenoids, chlorophylls, chlorophyll derivatives, and porphyrins. Optimal chromatographic systems (i.e., sorbents and mobile phases for each pigment group) are considered in detail in the review. The Isaksen (1991) review was revised and updated by Andersen and Francis (1996). 

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