Chemicals chlorophyll

Chemical degradation of chlorophyll gives a number of substances including phytol The constitution of phytol is given by the name 3 7 11 15 tetramethyl 2 hexadecen 1 ol How many stereoisomers have this constitution" ... 

In the post-World War II years, synthesis attained a different level of sophistication partly as a result of the confluence of five stimuli (1) the formulation of detailed electronic mechanisms for the fundamental organic reactions, (2) the introduction of conformational analysis of organic structures and transition states based on stereochemical principles, (3) the development of spectroscopic and other physical methods for structural analysis, (4) the use of chromatographic methods of analysis and separation, and (5) the discovery and application of new selective chemical reagents. As a result, the period 1945 to 1960 encompassed the synthesis of such complex molecules as vitamin A (O. Isler, 1949), cortisone (R. Woodward, R. Robinson, 1951), strychnine (R. Woodward, 1954), cedrol (G. Stork, 1955), morphine (M. Gates, 1956), reserpine (R. Woodward, 1956), penicillin V (J. Sheehan, 1957), colchicine (A. Eschenmoser, 1959), and chlorophyll (R. Woodward, 1960) (page 5). ... 

Several chemical transformations in the chlorin series were discovered during the course of Woodward s total synthesis of chlorophyll a.3a d An important reaction in the final steps of this total synthesis is the removal of an a-oxo acid ester residue from the 17-position of the chlorin 22, which proceeds very smoothly in the presence of base by a retro-aidol-type fragmentation to yield the chlorin isopurpurin methyl ester (23) which is also available by degradation of chlorophyll a, so that at this point of the synthesis synthetically derived material could be compared with an authentic sample prepared from natural chlorophyll a. 

The chemical structure of dinoflagellate luciferin was found to be a tetrapyrrole, possibly derived from chlorophyll (Nakamura et al., 1989). The luciferase of G. polyedra was cloned (Bae and Hastings, 1994). Recently, the crystal structure of the third domain of the luciferase was determined (Schultz et al., 2005). 

Fig. 8.8 The chemical structures of dinoflagellate luciferin (5), the product of luminescence reaction catalyzed by luciferase (6), air-oxidation product formed at — 20°C (7), and the blue oxidation product (8). Note structural resemblance between these compounds and chlorophylls.

FIGURE 2 Cold weather triggers chemical processes that reduce the amount of the green chlorophyll in leaves, allowing the colors of various other pigments to show. 

Photoautotrophic organisms, such as algae, cyanobacteria, and plants, all contain chlorophyll a and obtain energy by a process known as oxygenic photosynthesis. The overall chemical reaction of this process is ... 

Structures and Chemical and Spectroscopic Properties of Major Chlorophylls and Bacteriochlorophylls... 

RCC is very unstable and rapidly reduced to a primary fluorescent chlorophyll catabolite (pFCC) by red chlorophyll catabolite reductase (RCCR). In subsequent steps pFcc is converted to different fluorescent chlorophyll catabolites (FCCs). These chemically rather labile compounds are further converted into colorless nonfluorescing chlorophyll catabolites (NCCs) by a nonenzymatic deconjugation of the four... 

Carotenoids are also present in animal products such as eggs, lobsters, greyflsh, and various types of hsh. In higher plants, they occur in photosynthetic tissues and choloroplasts where their color is masked by that of the more predominant green chlorophyll. The best known are P-carotene and lycopene but others are also used as food colorants a-carotene, y-carotene, bixin, norbixin, capsanthin, lycopene, and P-apo-8 -carotenal, the ethyl ester of P-apo-8-carotenic acid. These are Upid-soluble compounds, but the chemical industry manufactures water-dispersible preparations by formulating coUoid suspensions by emulsifying the carotenoids or by dispersing them in appropriate colloids. ... 

Both chlorophylls and carotenoids occur in all green leaves, but their color is masked by chlorophyll in photosynthetic tissues. When the chlorophylls break down as leaves senesce (mature), the yellow and orange carotenoids persist and the leaves turn yellow. Carotenoids are responsible for the colors of familiar animals such as lobsters, flamingos, and fish. Often people are unaware of the chemical nature of food colorants. ... 

Commercially produced metal-substituted chlorophylls such as copper chlorophylls and copper chlorophyllins that can be obtained by chemical modification of natural chlorophylls have better stability, solubility, and tinctorial strength, but they cannot be considered natural food colorants and will be discussed later. 

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