Magnesium, chlorophyll intermediate

THE SYNTHESIS OF RADIOACTIVE PHOTOAFFINITY LABELS CONTAINING MAGNESIUM TETRAPYRROLE INTERMEDIATES OF CHLOROPHYLL AND BACTERIOCHLOROPHYLL BIOSYNTHESIS. 

Granik, S., Magnesium vinyl pheoporphyrin another intermediate in the biological synthesis of chlorophyll, J. Biol Chem., 183, 713, 1950. 

However, the process is very complex and involves several intermediates such as chlorophyll (of which there is more than one type). Chlorophylls are porphyrins that contain magnesium. The growth of plants is responsible for the production of oxygen in the atmosphere as well as food and natural fibers. 

The biochemical conversion of magnesium protoporphyrin mono-methylester to protochlorophyll probably also involves the primary formation of a jr-cation radical [Cox (41)]. Whether the hydrogenation of protochlorophyll to chlorophyll involves phlorin intermediates [Woodward (214)] is still not known. 

When ferrous iron is inserted into protoporphyrin, the ubiquitous iron porphyrin or heme is formed. Because of the resonating structure, an electron donor or acceptor molecule need not come in contact with the iron atom directly to oxidize or reduce the iron atom it is probably sufficient that contact be made with any portion of the resonating molecule for the iron atom to be oxidized or reduced. The oxidative properties of the iron atom in heme are modified by the iron being held in this ring and are further modified by the heme being attached to specific proteins. In nature the other metal that complexes with protoporphyrin is magnesium Mg protoporphyrin is an intermediate compound in the biosynthetic chain of chlorophyll synthesis. The movements of the ir electrons in the porphyrin are undoubtedly intimately connected with the functioning of the heme and chlorophyll structures, but of this we know very little. 

Biosynthesis.—Further evidence has been adduced for the formation of 5-ALA and magnesium protoporphyrin-IX from glutamate in greening plants,and the enzymic preparation of the monomethyl ester of magnesium protoporphyrin has been described." Intermediates in the last stages of chlorophyll biosynthesis in which the geranylgeranyl side-chain is converted into phytyl have been studied l- C-labelled acetate is incorporated into the expected alternate positions in the phytyl ester side-chain (as shown by C n.m.r. spectral studies), but only low incorporations of mevalonate were obtained, presumably because of poor transport into the cell. The biosynthesis of chlorophyll-f has also been studied." ... 

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