Occurrence, Formation, and Importance
Linear oligopyrroles may occur in organisms with respect to four functional aspects as shown schematically in Fig. 3–1: In the course of biosynthesis of cyclic tetrapyrroles like porphyrin (cytochromes, hemoglobin, myoglobin), chlorin (chlorophylls), bacteriochlorin (bacteriochlorophylls) and corrin (vitamin B12), linear di-, tri-, and tetrapyrroles are produced as open chain precursors (1). During metabolism of these cyclic tetrapyrroles linear oligopyrroles (mainly bile pigments) are the products of degradation. These linear oligopyrroles may be excreted (2), or they play a functional and thereby vital role (e.g. as photosensitizers in the conversion of light energy or as optical information transmitters) mostly attached to membranes of the organism in question (3), or finally, they may become incorporated and deposited into certain tissues or even skeletal parts where they serve no obvious function apart from coloring (4).
KeywordsHeme Oxygenase Levulinic Acid Couple Oxidation Bile Pigment Porphobilinogen Deaminase
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