Isolation from microorganisms

The flavodoxins are a group of FMN containing flavoproteins isolated from microorganisms which mediate electron transfer at a low redox potential between the... 

Enzymes that directly incorporate molecular oxygen into organic substrates play a crucial role in many fundamental biological processes such as degradation of natural products in the biosphere, biosynthesis and metabolism of amino acids, hormones, drugs, etc. A wide variety of enzymic oxygenases has been identified and isolated from microorganisms, plants and animals. A detailed description of these enzymes is beyond the scope of this chapter, but several books and review articles are available.1,58-62... 

Such conversions in mammals are not very efficient, however, with the exception of, perhaps, the orotate phosphoribosyltransferase, which is a component of the pyrimidine nucleotide biosynthetic pathway (Figure 10.9). A very active uracil phosphoribosyltransferase has been isolated from microorganisms. It converts uracil to UMP using PRPP. 

Several glycosylpurines have been isolated from microorganisms (Table 40) and proved to have substantial biological activity (B-70MI40900). They include substances such as 9-(jS-D-arabinofuranosyl)adenine (Ara A) which is a powerful antiviral and antitumour agent and... 

Alkaloids are an important class of compounds that have pharmacological effects on various tissues and organs of humans and other animal species. More than 16,000 are known and most are derived from higher plants. Alkaloids have also been isolated from microorganisms, from marine organisms such as algae, dinoflagellates, and puffer fish, as well as from terrestrial animals, such as insects, salamanders, and toads. 

Finally, enzyme isolation from microorganisms allows the application of biocatalysts in many other fields and products such as laundry detergents (with the washing machine as reactor), food (cheese, bread), drinks (juice, beer, wine), and feed (enzymes as digestion aid). The food and feed industries in particular replace more and more additives by enzymes, i.e. eatable and digestible catalysts, that result in comparable or even better functional products. 

More than 10,000 enzymes occur in nature. Of these, approx. 3,000 are characterized. Approx. 800 are commercially available, but only approx. 20 in industrial amounts (predominantly hydrolases and oxidoreductases). They are isolated from microorganisms, plants, or animals. Lipases (which belong to the class of hydrolases) and oxidoreductases catalyze, for example, the reactions depicted in Fig. 3.6. Note that all reactions are reversible. Examples of flavouring substances that are produced with lipases and oxidoreductases are shown in Tab. 3.12. 

Triacetic acid lactone (1) is one of the simplest polyketides, and its formation from acetyl-CoA and malonyl-CoA has been proved (68JBC5471). Biogenetic formation of triacetic acid lactone has been considered a derailment from fatty acid biosynthesis promoted by the absence of the reductant NADPH (69MII). Pyrone 1 has been isolated from microorganisms (67JA676) and is transformed into tropolone derivatives by Penicillium stipitatum (67JA681). 

Alternative hydrolytic enzymes, such as amidases and acylases, have also been employed for the resolution of racemic amines. Unlike lipases, these enzymes are typically not commercially available but they can be isolated from microorganisms. 

Methylcobalamin (2 c) can be isolated from microorganisms. Its largely covalent Co—CH3 bond undergoes all three possible types of reactions, namely homolysis, carbonium-ion transfer, and carbanion transfer (Scheme 1), thus including reduction and oxidation of cobalt, respectively. Thermal degradation of cobalamin preferentially yields methane and ethane as radical-type reaction products (cf. 

Acetylenes, few of which are biologically active, have also been isolated from microorganisms and marine organisms, such as the antifungal acetylenic cyclohexene-epoxide derivative asperpentyn isolated from Aspergilus and dactylyne, an acetylenic dibromochloro-ether, isolated from sea hare. Dactylyne was shown to be a very potent inhibitor of drug metabolism... 

The facile conversion of the 6,8-dioxabicyclo[3.2.1]octanes to chiral pyrans is exploited in steps towards the synthesis of ( —)-(6 S, l iS)-pestalotin (478), a gibberellin synergist isolated from microorganisms. Treatment of either tosylate 471 or mesylate 476 with lithium di- -... 

The name antibiotic was coined for substances isolated from microorganism growth media that had potent antibacterial, antifungal, antineo-plastic, and so on, activity. The well-known antibacterial penicillin G was the first to be discovered. Its activity was noted by Fleming in England in 1929, but the work of Florey and Chain in Oxford during... 

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