Synthesis bacterial

Bacteria can s mthesize a wide range of biopolymers. The key aspects of the production bacterial biopolymers have been reviewed (75,76). It is expected that a better understanding of polymer biosynthesis and material properties can lead to an increased use of bacterial biopol mers. 

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Penicillins and other /3-lactam antibiotics (see the Focus On in this chapter) typically develop a resistance to bacteria due to bacterial synthesis of /Mactamase enzymes. Tazobactam, however, is able to inhibit the activity of the /3-lactamase by trapping it, thereby preventing resistance from developing. 

Mansouri S, AW Bunch (1989) Bacterial synthesis from 2-oxo-4-thiobutyric acid and from methionine. J Gen Microbiol 135 2819-2827. 

E. J. Hehre and D. M. Hamilton, Bacterial synthesis of an amylopectin-like polysaccharide from sucrose, J. Biol. Chem., 166 (1946) 77-78. 

Is rifaximin, a rifampin-like antimicrobial agent that inhibits bacterial synthesis of RNA, an ideal agent for the... 

Once a suitable crystal is obtained and the X-ray diffraction data are collected, the calculation of the electron density map from the data has to overcome a hurdle inherent to X-ray analysis. The X-rays scattered by the electrons in the protein crystal are defined by their amplitudes and phases, but only the amplitude can be calculated from the intensity of the diffraction spot. Different methods have been developed in order to obtain the phase information. Two approaches, commonly applied in protein crystallography, should be mentioned here. In case the structure of a homologous protein or of a major component in a protein complex is already known, the phases can be obtained by molecular replacement. The other possibility requires further experimentation, since crystals and diffraction data of heavy atom derivatives of the native crystals are also needed. Heavy atoms may be introduced by covalent attachment to cystein residues of the protein prior to crystallization, by soaking of heavy metal salts into the crystal, or by incorporation of heavy atoms in amino acids (e.g., Se-methionine) prior to bacterial synthesis of the recombinant protein. Determination of the phases corresponding to the strongly scattering heavy atoms allows successive determination of all phases. This method is called isomorphous replacement. 

Pharmacology SMZ inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid. TMP blocks the production of tetrahydrofolic acid by inhibiting the enzyme dihydrofolate reductase. 

The mechanism for bacterial synthesis of PHA is not the simple dehydration reaction between alcohol and carboxyl groups. It is more complicated and involves the coenzyme A thioester derivative of the hydroxyalkanoic acid monomer (produced from the organic feedstock available to the bacteria) [Kamachi et al., 2001], Growth involves an acyl transfer reaction catalyzed by the enzyme PHA synthase (also called a polymerase) [Blei and Odian,... 

The K vitamins include vitamin Ki, phylloquinone or phytonadione, and vitamin K2 which is a group of compounds, the menaquinones. Menadione, vitamin K3, is a precursor of menaquinone-4. Vitamin K is present in alfalfa and fish livers. Other dietary sources include green vegetables, soybean oil and eggs. A normal diet together with the bacterial synthesis of vitamin K in the gut are usually sufficient to prevent deficiencies in healthy adults. 

Trimethoprim-sulfamethoxazole (TMP-SMX) was introduced as a fixed dose combination in 1968. Trimethoprim was added to sulfamethoxazole to synergisti-cally and sequentially inhibit bacterial synthesis of tetrahydrofolic acid. The combination was also designed to delay development of bacterial resistance. Sulfamethoxazole was selected in part because it is a congener of the frequently used sulhsoxazole but exhibits slower enteric absorption and urinary excretion. Sulfamethoxazole has a half-life similar to that of trimethoprim. 

Mecfianism of Action A sulfonamide and folate antagonist that blocks bacterial synthesis of essential nucleic acids. Therapeutic Effect Bactericidal in susceptible microorganisms. 

Mechanism of Action Interferes with DNA gyrase, an enzyme which is needed for bacterial synthesis... 

Sulfonamides are structural analogs of PABA that competitively inhibit bacterial synthesis of folic acid (see p. 371). Because purine synthesis requires THF as a coenzyme, the sulfa drugs slow down this pathway in bacteria. 

Vitamin K is found in cabbage, cauliflower, spinach, egg yolk, and liver. There is also extensive synthesis of the vitamin by the bacteria in the gut. There is no RDA for vitamin K, but 70 to 140 mg/day is recommended as an adequate level. The lower level assumes one half of the estimated requirement comes from bacterial synthesis, whereas the upper figure assumes no bacterial synthesis. 

Factors which cause a decrease in bioavailability include 111 high urinary excretion (2) destruction by certain mlesiinal bacteria (2) increased urinary excretion caused by vitamin C (4) presence of sulfonamides which block intestinal synthesis and (5) a decrease in absorption mechanisms. Increase in bioavailability can be provided by stimulating intestinal bacterial synthesis in certain species. No toxicity due to folic acid has been reported in humans. 

In connection with the bacterial synthesis of CH3COOH and some other enzymatic insertion processes it can be envisaged that photoinsertion reactions deserve more attention in the future. 

Strittmatter P., Thiede M. A., Hackett C. S. and Ozols J. (1988) Bacterial synthesis of active rat stearoyl-CoA desaturase lacking the 26-residue amino-terminal amino acid sequence. J. Biol. Chem. 263, 2532-2535. 

Ruminant animals obtain their B12 from bacterial synthesis that takes place in the rumen. As a result, these animals may suffer from vitamin B12 deficiency when they are grazed on cobalt-deficient pastures because the rumen bacteria will be unable to produce the vitamin. 

The vitamin B12 that occurs in nature is produced almost entirely by bacterial synthesis in animals but not in humans (Battersby, 1994). The richest dietary sources of vitamin B12 are organ meats, such as fiver and kidney. Lesser amounts are present in shellfish, chicken, fish, muscle meats, and dairy products (the principal source in lacto-vegetarians). Plants contain no vitamin B12 unless they are contaminated by bacteria, and foods that contain microorganisms often provide the only source of vitamin B12 for strict vegetarians, such as the vegans of southern India. 

With the onset of the Second World War, Stephenson studied acetone-butyl alcohol fermentation as a means of synthesis of industrial solvents. Of greater importance was her work on pathogenic bacteria and her contributions to the MRC Committee on Chemical Microbiology. After the War, she studied the bacterial synthesis of acetylcholine in sauerkraut, while her last years were spent on an investigation of nucleic acids in bacteria and of their breakdown by enzymes within the cells. 

Kumar U, Shete A, Harle AS, Kasyutich O, Schwarzacher W, Pundle A, Poddar P. (2008) Extracellular bacterial synthesis of protein functionalized ferromagnetic C03O4 nanocrystals and imaging of... 

The determination of vitamin K requirements is complicated by the intestinal bacterial synthesis of menaquinones and the extent to which these are absorbed and utilized (Section 5.1). Prolonged use of antibiotics leads to impaired blood clotting, but simple dietary restriction of vitamin K results in prolonged prothrombin time and increased circulating preprothrombin so it is apparent that bacterial synthesis is inadequate to meet requirements in the absence of a dietary intake of phylloquinone. Preprothrombin is elevated at intakes between 40 to 60 /xg per day, but not at intakes above 80 /rg per day (Suttie etal., 1988). 

Dietary deficiency is relatively widespread, yet is apparently never fatal there is not even a clearly characteristic riboflavin deficiency disease. In addition to intestinal bacterial synthesis of the vitamin, there is very efficient conservation and reutilization of riboflavin in tissues. Flavin coenzymes are tightly enzyme bound, in some cases covalently, and control of tissue flavins is largely at the level of synthesis and catabolism of flavin-dependent enzymes. 

Intestinal bacteria synthesize riboflavin, and fecal losses of the vitamin may be five- to six-fold higher than intake. It is possible that bacterial synthesis makes a significant contribution to riboflavin intake, because there is carrier-mediated uptake of riboflavin into colonocytes in culture. The activity of the carrier is increased in riboflavin deficiency and decreased when the cells are cultured in the presence of high concentrations of riboflavin. The same carrier mechanism seems to be involved in tissue uptake of riboflavin (Said et al., 2000). 

As a result of this resorption and the protein binding of plasma biotin, which reduces filtration at the glomerulus, renal clearance of biotin is only 40% of that of creatinine. This efficient conservation of biotin, together with the recycling of biocytin released from the catabolism of biotin-containing enzymes, may be as important as intestinal bacterial synthesis of the vitamin in explaining the rarity of deficiency. 

On the basis of studies in patients who developed deficiency during total parenteral nutrition, and who are therefore presumably wholly reliant on an exogenous source of the vitamin - with no significant contribution from intestinal bacterial synthesis - the provision of 60 fxg of biotin per day for adults receiving total parenteral nutrition is generally recommended (Bitsch et al., 1985). 

Pantothenic acid is widely distributed in foods, and because it is absorbed throughout the small intestine, it is likely that intestinal bacterial synthesis also makes a contribution to pantothenic acid nutrition. As a result, deficiency has not been unequivocaUyreportedinhumanbeings except in specific depletion studies, which have also frequently used the antagonist < -methyl pantothenic acid. 

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