Incorporation rate

Both H-thymidine incorporation and radiolabeled leucine incorporation techniques have been recently used to determine bacterial activity and growth in the rhizosphere of barley seedling (28), Bacteria were initially released from the rhizosphere using homogenization and centrifugation before adding the labeled substrates. The cell incorporation rate was twice as high in the rhizosphere than in bulk soil. In addition, both the leucine and thymidine incorporation rates increased with the distances from the root tip (28). 

The binding of carotenoids within the lipid membranes has two important aspects the incorporation rate into the lipid phase and the carotenoid-lipid miscibility or rather pigment solubility in the lipid matrix. The actual incorporation rates of carotenoids into model lipid membranes depend on several factors, such as, the kind of lipid used to form the membranes, the identity of the carotenoid to be incorporated, initial carotenoid concentration, temperature of the experiment, and to a lesser extent, the technique applied to form model lipid membranes (planar lipid bilayers, liposomes obtained by vortexing, sonication, or extrusion, etc.). For example, the presence of 5 mol% of carotenoid with respect to DPPC, during the formation of multilamellar liposomes, resulted in incorporation of only 72% of the pigment, in the case of zeaxanthin, and 52% in the case of (1-carotene (Socaciu et al., 2000). A decrease in the fluidity of the liposome membranes, by addition of other... 

Table 9.2 Incorporation rate of [2-14C]-pyruvate into monoterpenes of isolated peppermint oil gland secretory cells in the presence of fosmidomycin, a specific inhibitor of 1-deoxy-D-xylulose 5-phosphate reductoisomerase, an enzyme of the mevalonate-independent pathway of isoprenoid biosynthesis.

The kinetics of complex formation with Zn2+ can be followed by monitoring the change in the fluorescence intensity [ 17g]. In the case of 1, the change in the fluorescence intensity with time indicates a biphasic kinetics with the incorporation rate constants k1 = 4.9 x 105 M 1 s 1 followed by a first order process... 

Mandelate racemase, another pertinent example, catalyzes the kinetically and thermodynamically unfavorable a-carbon proton abstraction. Bearne and Wolfenden measured deuterium incorporation rates into the a-posi-tion of mandelate and the rate of (i )-mandelate racemi-zation upon incubation at elevated temperatures. From an Arrhenius plot, they obtained a for racemization and deuterium exchange rate was estimated to be around 35 kcal/mol at 25°C under neutral conditions. The magnitude of the latter indicated mandelate racemase achieves the remarkable rate enhancement of 1.7 X 10, and a level of transition state affinity (K x = 2 X 10 M). These investigators also estimated the effective concentrations of the catalytic side chains in the native protein for Lys-166, the effective concentration was 622 M for His-297, they obtained a value 3 X 10 M and for Glu-317, the value was 3 X 10 M. The authors state that their observations are consistent with the idea that general acid-general base catalysis is efficient mode of catalysis when enzyme s structure is optimally complementary with their substrates in the transition-state. See Reference Reaction Catalytic Enhancement... 

The second strategy for the chemoenzymatic synthesis of block copolymers from enzymatic macroinitiators employs an individual modification step of the enzymatic block with an initiator for the chemical polymerization (route B in Fig. 4). This strategy has the advantage that it does not depend on a high incorporation rate of the dual initiator. On the other hand, quantitative end-functionalization becomes more... 

Olaquindox is an antibacterial also used as a growth promoter for swine at an incorporation rate in feeds of 25-100 ppm. In swine, olaquindox is metabolized either by oxidation of the alcohol group on the side chain or removal of one or both of the A-oxide groups at the positions 1 and 4 on the quinoxaline ring. 

Solid-Phase Chemical Equilibrium. For the growth of multicomponent films, the solid film composition must be predicted from the gas-phase composition. In general, this prediction requires detailed information about transport rates and surface incorporation rates of individual species, but the necessary kinetics data are rarely available. On the other hand, the equilibrium analysis only requires thermodynamic data (e.g., phase equilibrium data), which often are available from liquid-phase-epitaxy studies, as discussed by Anderson in Chapter 3. 

However, whole soybeans may have adverse effects on the carcass fat of broilers. A standard recommendation is that the soybean product should be limited to supplying a dietary addition of 20g/kg soybean oil in order to ensure an acceptable carcass fat quality and good pellet quality. This may require that the incorporation rate of soybeans in the feed of finishing broilers should not exceed lOOg/kg. 

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