Biosynthesis time course

Experiments were carried out by varying the amount of inoculum (10, 15 and 20 % v/v) to determine the optimal quantity which ensures a steady growth. The time course of growth of the cell suspensions, inoculated with the corresponding amount of inoculum was traced by day-to-day determining the yield of dry cell biomass (7), while the time course of biosynthesis of extracellular polysaccharides was followed by their daily determination, using the carbazole method (9). 

Fig. 2. Time course of biosynthesis of polysaccharides from a cell suspension of Helianthus annuus 1805.

Fig. 2 Time course of biosynthesis secretion of polygalacturonase from annuus 1805.

Fig. 3 Time course of biosynthesis and secretion of pectinmethylesterase from H. annuus 1805.

Figure 5. Comparison of the time course of PGH2 biosynthesis, BP-7,8-dihydrodiol metabolism, and generation of a mutagen from BP-7,8-dihydrodiol by RSVM. (Reproduced with permission from Ref. 30. Copyright 1982 Marcel Dekker.)...

Figure 3 Biosynthesis and purification of 90-kD elastin analogue analyzed by denaturing polyacrylamide gel electrophoresis (10-15% gradient, visualized by silver staining). Lanes 1-7 time course of target protein expression at 0, 30, 60, 90, 120, 150, and 180 minutes after induction. Lane 9 soluble lysate of induced E. coli expression strain BLR(DE3)pRAMl. Lanes 10-13 protein fractions obtained from immobilized metal affinity chromatography of the lysate on nickel-NTA agarose (imidazole gradient elution). Lanes 8,14 protein molecular weight standards of 50, 75, 100, and 150 kD.

Investigations of isoprenoid metabolism and biochemistry in plants have been hampered for several reasons. Some isoprenoids accumulate over long developmental time courses, which suggests that the enzymes responsible for their biosynthesis are either present in low abundance or have low activity levels. Sterols... 

WALDHAUSER, S. S. M KRETSCHMAR, J. A., BAUMANN, T. W N-methyltransferase activities in caffeine biosynthesis Biochemical characterization and time course during leaf development of Coffea arabica., Phytochemistry., 1997, 44, 853-859. 

Figure 35 Conversion of LctA to the mature form of lacticidin 481 catalyzed by LtcM. (a) Thioether bridge formation in lantibiotic biosynthesis leading to dehydration (-18 Da), (b) MS time course of isotopically depleted LctA conversion to lacticidin 481 by LtcM shows that little dehydration intermediates are observed.

Monoterpene biosynthesis has been studied in conifers using labeled precursors such as carbon dioxide, acetate and mevalonate (63,64). Specifically labeled precursors have been employed to deduce mechanistic features of a-plnene (65,66) and 3-carene (67,68) biosynthesis in pine species. Glelzes and co-workers (69) have argued, by way of time-course studies, that the initial formation of acyclic hydrocarbons (oclmene, myrcene) from C02 in Pinus pinaster needles indicated that these olefins serve as precursors to cyclic monoterpenes (a-plnene, 8-pinene) by a reversible protonatlon mechanism. These suggestions, however, are without precedent, and run counter to direct evidence demonstrating that the cyclizatlon of geranyl pyrophosphate occurs without the involvement of free intermediates (17). 

MCGUIRE, S.M., TOWNSEND, C.A., Demonstration of a Baeyer-Villiger oxidation and the time course of cyclization in bisfuran ring formation during aflatoxin B biosynthesis. Bioorgan. Medicin. Chem. Lett., 1993, 3, 653-656. 

The site of heme synthesis for leghemoglobin in nodules has been proposed as being in the bacteroids on the basis of studies examining the incorporation of 8-amino[4- C]levulinic acid into haem in different fractions from legume nodules (Cutting and Schulman, 1969 Godfrey and Dilworth, 1971). Support for this hypothesis has been obtained from studies showing that the level of 8-aminolevulinic acid synthase, a key enzyme in porphyrin biosynthesis, increases in bacteroids from soybean over the same time course as... 

A splendid illustration of the use of 500 MHz NMR is provided by the water suppressed time course of porphyrin biosynthesis where porphobilinogen (PEG), the substrate for uro gens I and m and Vitamin 3 2 is transformed into the apparent product uro gen I which turns out to be a chemical artifact. Thus, during incubation of PEG with the enzyme, PEG deaminase ([D] Fig. 1 Mj. 33,000) the product released from the enzyme is pre-uro gen, or hydroxymethyl bilane (HME), whose characteristic spectrum (Fig. 1) (t 2 = 180 sec/30 C) can be seen transiently when the reaction is carried out at 4 C [12a,b]. The NMR method also uniquely defines HME as the substrate for the second enzyme, uro gen ni cosynthetase. In the absence of the latter enzyme, the cyclization of the head-to-tail tetrapyrrole HME takes place spontaneously. The deep-seated intra-molecular rearrangement of HME to uro gen El can now be studied by this technique. 

Evidence for conjugate reduction as a key step in monot-erpene biosynthesis has been obtained from studies of the oxygenated monoterpenes of Mentha piperita (Fig. 19.10) (Croteau, 1984). The pathway from isopiperitenone to the menthol esters was deduced largely by time-course studies and direct feeding experiments. Other evidence supports the intermediacy of /-limonene (11) as the first cyclization product of GPP in this plant. This is followed by the adlylic oxidation of the olefin and subsequent isomerization and reduction of the double bonds of isopiperitenone to the men-thones (such as 26). Furthermore, stereospecific dehydrogenases responsible for the synthesis of /-menthol (27) and d-neomenthol (28) have been isolated (Croteau, 1984). 

Fig. 7. Time course of light-induced flavonoid accumulation and activities of enzymes of fla-vonoid biosynthesis in cell cultures of Petroselinum hortense...

Fig. 8. Time course of the activities of enzymes of alkaloid biosynthesis and of the rates of lakaloid formation in hyphae of Penicillium cyclopium...

The shifts in ion concentration may alter the lipid labeling by either a secondary effect or a direct action on the metabolic steps. In either case, the early time-course of the labeling suggests that the precursor can enter different pools of retina lipids and that different branches of the de novo biosynthesis of retina glycerolipids are very sensitive to shifts in the ionic environment. Further experiments with lower concentrations of X-537A as well as with another carboxylic acid lipid soluble ionophore will likely help in clarifying the dual effect shown here to be exerted by this antibiotic. 

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