Linear tetrapyrrole compounds

Synthesis of Macrocyclic and Linear Tetrapyrrole Compounds Corrinoid Compounds in Edible Cyanobacteria... 

Here, we reviewed recent studies that characterize the physiological functions of macrocylic and linear tetrapyrrole compounds from edible cyanobacteria. 

FIGURE 1 Biosynthesis of major macrocyclic and linear tetrapyrrole compounds in cyanobacteria. 

Interesting tautomeric possibilities exist in the xanthobilirubic acid series (cf. reference 57) which can be illustrated by the equilibrium 62 63, More complex examples of the same type are found among the linear tetrapyrrole pigments— the bilenes, bilidienes, and bili-trienes—and have been discussed by Stevens. Relatively little evidence is available concerning the fine structure of these compounds, although the formation of complexes has been advanced as evidence for the 0X0 structure in some cases. ... 

It is necessary to devote a specific section to the nomenclature of corrinoids and of their linear tetrapyrrolic precursors because of the confusion existing in the literature about the correct naming of these compounds. 

B,C,D-Ni(AXDC) fills the last gap in the corrin family and its preparation has been reported by Monforts [76, 77]. This compound has been obtained by cyclization of a Ni complex of the linear tetrapyrrole reported in Fig. 28. The synthetic pathway is similar to that reported for tetradehydrocorrins a cyano group is utilized to protect the 1-position and then removed by alkaline hydrolysis. Cyclization may be acid catalyzed at room temperature, or accomplished thermally at 240-260 °C, with similar yields. 

Substantial quantities of edible cyanobacteria are produced globally to meet the high demands of both food and pharmaceutical industries. These cyanobacteria contain substantial quantities of phycobiliproteins, of which phycocy-anin, in particular, has various therapeutic effects owing to the linear tetrapyrrole chromophore phycocyanobilin. Cyanobacteria can also synthesize macrocyclic tetrapyrrole corrinoid compounds. However, various edible cyanobacteria contain substantial quantities of inactive pseudo-Bi2 rather than active Bi2- To overcome this nutritional defect of edible cyanobacteria, it is vital to determine the genetic, biochemical, and physiological properties of pseudo-Bi2-... 

Propionic acid bacteria can synthesize a number of tetrapyrrole compounds corrinoids, heme, heme-containing enzymes, cytochromes, and linear tetrapyrroles. Biosynthesis of tetrapyrroles by all microorganisms starts with the formation of 5-aminolevulinic acid (ALA) (Corcoran and Shemin, 1957) and proceeds through the formation of porphobilinogen (PBG) and uroporphyrinogen (UPB) (Fig. 4.19A). Of the four possible isomers of uroporphyrinogenes, only the derivatives of UPB III are found in nature. 

Pyrrolas, pyrrole derivatives compounds containing the pyrrole ring. They are subdivided into mono-, di-, tri- and tetrapyrroles. Tetrapyrroles may be non-cyclic or cyclic. Bile pigments (see) and the chromo-phores of Biliproteins (see) are linear, while Porphyrins (see) and Corrinoids (see) are cyclic tetrapyrroles. 

A number of biologically important compounds contain substituted pyrroles in cyclic or linear array. With the exception of the corrin nucleus of vitamin 8 2 in which one methylene bridge is missing, the. cyclic tetrapyrroles can be regarded as derivatives of the parent porphin, the structure of which is given in Figure 38. The porphyrins... 

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