Bacteria enzyme systems

Figure 3 Some interactions between gastrointestinal bacteria and the xenobiotic metabolizing enzyme system of the host. Solid lines, host XME system reactions dotted lines, classes of reactions mediated by gastrointestinal bacteria. Specific examples of reaction classes 1-5 are cited in the text. (Modified from Rowland and Tanaka " )...

Bacteria are vulnerable to the selective attack of chemotherapeutic agents because of the many metabolic and molecular differences between them and animal cells. The biology of vims replication, with its considerable dependence on host-cell energy-producing, protein-synthesizing and biosynthetic enzyme systems, severely limits the opportunities for selective attack. Another problem is that many vims diseases only become apparent after extensive viral multiplication and tissue damage has been done. 

The 3-ketothiolase has been purified and investigated from several poly(3HB)-synthesizing bacteria including Azotobacter beijerinckii [10], Ral-stonia eutropha [11], Zoogloea ramigera [12], Rhodococcus ruber [13], and Methylobacterium rhodesianum [14]. In R. eutropha the 3-ketothiolase occurs in two different forms, called A and B, which have different substrate specificities [11,15]. In the thiolytic reaction, enzyme A is only active with C4 and C5 3-ketoacyl-CoA whereas the substrate spectrum of enzyme B is much broader, since it is active with C4 to C10 substrates [11]. Enzyme A seems to be the main biosynthetic enzyme acting in the poly(3HB) synthesis pathway, while enzyme B should rather have a catabolic function in fatty-acid metabolism. However, in vitro studies with reconstituted purified enzyme systems have demonstrated that enzyme B can also contribute to poly(3HB) synthesis [15]. 

Bacteria, Aberdeen, UK), was found to have a highly active nitrile hydratase/amidase enzyme system, based on whole-cell biotransformation experiments. Subsequently, individual enzymes (nitrile hydratase and amidase) from this strain were cloned and expressed separately in E. coli However, distribution of some strains or other materials from these public collections may be limited, usually as a result of the restrictions on their commercial use imposed by intellectual property rights. 

The system can be applied for examination of control mechanisms of metabolic coupled enzyme systems, such as the sugar transport system in bacteria. 

Another source of rubredoxins was found in an aerobic bacterium, Pseudomonas oleovorans, utilizing n-hexane as a carbon source (10). This particular rubredoxin differs from those commonly found in anaerobic bacteria in some of its properties it has a molecular weight of 19,000, and one iron form of the protein is readily converted to a two-iron form (11). The rubredoxin of P. oleovorans functions as a terminal electron transfer component in an enzyme system which participates in the ( -hydroxylation of fatty acids and hydrocarbons. The hydrocarbon-oxidizing... 

These heteropentalenes are also toxic to bacteria cells Escherichia coli. Penetrating into the cells they are reduced by an enzyme system and then convert O2 to toxic O2 and H2O2 returning themselves to the initial state <89Mi 4ii-0l>. Activity as an oxygen promotor with catalase and superoxidase was found for (5 X = S) in concentrations down to 0.005 mM <89JAP8966120>. 

PAN was for a long time thought to be resistant to microbial attack. However, various bacteria that produced nitrile-converting enzymes were isolated from waste-waters of factories producing PAN fibre. Eor example, a nitrile hydratase/amidase enzyme system was studied from Mesorhizobium sp. E28 [68]. Also, bacteria (namely Ralstonia solanacearum and Acidovorax avenae) were used for the removal of acrylic acid from such waste-waters [69]. Later, on the basis of NMR... 

The determination of the endotoxin with limulus amebocyte lysate (LAL) is based on gel formation of a mixture consisting of a solution of endotoxin of Gram-negative bacteria with a solution of lysate. The extent and speed of the reaction depend on the endotoxin concentration, pLL, and temperature. The reaction requires the presence of certain cations, a proclotting enzymes system, and clottable protein, which are produced by lysate. 

It was long believed that bacteria were unique in their ability to denitrify. However, Shoun and Tanimoto (1991) and Shoun et al., (1989) demonstrated that the fungus, Fusarium oxysporum, could be induced to synthesize an enzyme system capable of the anaerobic reduction of nitrite to N2O. Induction occurred under conditions of low oxygen concentrations in the presence of nitrate or nitrite. One and pethaps the only component of this nitrite reductase system is a unique, soluble cytochrome P-450 (P-450dNIR), which is more similar in its cDNA-inferred amino acid sequence to soluble, bacterial P-450 enzymes (espe-... 

This substance inhibits the growth of bacteria by interfering with the synthesis of folic acid, 7, which is an essential substance for bacteria and animals alike. However, animals acquire folic acid from a normal diet, whereas bacteria have to synthesize it. Biosynthesis of folic acid is blocked by 4-aminobenzenesulfonamide, probably because of the structural similarity of the sulfonamide to 4-aminobenzoic acid, which is a normal ingredient in the biosynthesis of folic acid. The enzyme system involved apparently substitutes the sulfonamide for... 

This microbial sensor system is based on the inhibitory action of the mutagens on the respiration of B subtilis Rec . B subtilis M45 (Rec") is genetically deficient in the DNA recombination enzyme system, whereas B subtilis H17 (Rec+) is a wild strain which has the ability to repair damaged DNA. The subsequent death of Rec bacteria is preceded by the decrease of respiration. As a result, the number of Rec cells on the surface of the oxygen electrode decreased and the current of the Rec electrode increased. On the other hand, the damaged DNA of Rec+ bacteria is repaired with the recombination system. Therefore, the number of Rec+ cells did not change and the current of the Rec electrode did not increase. 

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