Microorganisms pterins

Pterins make no contributions to the colors of plants and microorganisms. One important pterin is the folate produced by plants and microorganisms. Folate and its derivatives are present in plants in various concentrations in mitochondria, cytosols, vacuoles, and plastids. The total amount of fohc acid depends on the plant species, on the developmental stage, and on external factors. Good sources of folates are beans, lentils, spinach, and wheat germ. ... 

The precursors for riboflavin biosynthesis in plants and microorganisms are guemosine triphosphate and ribulose 5-phosphate. As shown in Figure 7.3, the first step is hydrolytic opening of the imidazole ring of GTP, with release of c2irbon-8 as formate, and concomitant release of pyrophosphate. This is the same as the first reaction in the synthesis of pterins (Section 10.2.4), but utilizes a different isoenzyme of GTP cyclohydrolase (Bacher et al., 2000, 2001). 

The photoreceptor molecules used by different microorganisms for light perception vary significantly and fall in different classes including BLUE proteins, cryptochromes, phototropins, phytochromes, and rhodopsins. Other prokaryotic and eukaryotic organisms use photoactive yellow proteins (PYP) which contain a 4-hydroxycinnamate chromophore (21)., chlorophylls, carotenoids, phycobilins, and pterins. Hypericins have been found to be involved in photoorientation of ciliates (22). 

Flavin and pterin accessory chromophores (in cryptochrome and phototropin pigments these are blue-Kght receptors in plants and microorganisms and, in the case of cryptochromes, in animals too)... 

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