Relative activities

Parameter Source Worker activity Relative importance Control... 

Whereas introducing a thiol moiety at C-7 markedly reduced the antibacterial activity relative to lincomycin (79), the 7(3)-7-deoxy-7-alkylthiolincomycins exhibited considerably enhanced antibacterial activity without apparent regard for the size of the alkyl group (80—82). A marked increase in gram-negative activity was shown when the 7(3)-substituent contained a 2- or 3-hydroxy or amino group, but this activity was insufficient to be effective in infected mice (83—85). 

The acid-instabihty of erythromycin makes it susceptible to degradation in the stomach to intramolecular cyclization products lacking antimicrobial activity. Relatively water-insoluble, acid-stable salts, esters, and/or formulations have therefore been employed to protect erythromycin during passage through the stomach, to increase oral bioavakabihty, and to decrease the variabiUty of oral absorption. These various derivatives and formulations also mask the very bitter taste of macroHdes. 

It is notable that pyridine is activated relative to benzene and quinoline is activated relative to naphthalene, but that the reactivities of anthracene, acridine, and phenazine decrease in that order. A small activation of pyridine and quinoline is reasonable on the basis of quantum-mechanical predictions of atom localization encrgies, " whereas the unexpected decrease in reactivity from anthracene to phenazine can be best interpreted on the basis of a model for the transition state of methylation suggested by Szwarc and Binks." The coulombic repulsion between the ir-electrons of the aromatic nucleus and the p-electron of the radical should be smaller if the radical approaches the aromatic system along the nodal plane rather than perpendicular to it. This approach to a nitrogen center would be very unfavorable, however, since the lone pair of electrons of the nitrogen lies in the nodal plane and since the methyl radical is... 

Monomer System Alkyl chain % active (rel. to monomer) Approx, particle size Polymer use... 

The data in Figure 2.12 are the results of initial mutagenesis experiments, which does not yet constitute directed evolution. An evolutionary process was subsequently induced by combining the mutations of two improved mutants of the first round [46]. Thereby new mutants were obtained, which show an increase of activity relative to the WT by more than 2 orders of magnitude. Although enantioselectivity was not the... 

Redwood City, California, and Roche) and two clones have been selected for their improved in vitro activity relative to human IFN-a. One of them has been pegylated but its development has been halted because of strong immune reaction. 

Pharmacological activity Relatively strong macrophage FcR expression enhancing activity Not reported... 

Rekker, R. E., Mannhold, R., Bijloo, G., De Vries, G Dross, K. The lipophilic behaviour of organic compounds 2. The development of an aliphatic hydrocarbon/ water fragmental system via interconnection with octanol-water partitioning data. Quant. Struct.-Activ. Rel. 1998, 37, 537-548. 

Prolonged seasoning of the adsorbent in triplet oxygen leads to loss of the adsorbent s activity relative to the adsorption of 02( A ). This... 

The feed stream consists of 60 mole percent hydrogen, 20% nitrogen, and 20% argon. Calculate the composition of the exit gases, assuming equilibrium is achieved in the reactor. Make sure that you take deviations from the ideal gas law into account. The equilibrium constant expressed in terms of activities relative to standard states at 1 atm may be assumed to be equal to 8.75 x 10 3. The fugacity of pure H2 at 450 °C and 101.3 MPa may be assumed to be equal to 136.8 MPa. 

However, these elegant glycosylated nanostructures displayed only weak biological activity relative to their native glucan elicitor counterparts. Nevertheless, such glycoclusters provided unique environments for host-guest chemistry of amphi-pathic molecules owing to their lipophilic core surrounded by a hydrophilic periphery. 

The obvious disadvantage of immunoassays is that immunological reactivity cannot be guaranteed to correlate directly to biological activity. Relatively minor modifications of the protein product, although having a profound influence on its biological activity, may have little or no influence on its ability to bind antibody. 

Subsea hydrothermal vents, as mentioned in the previous section, are sites of intense biological activity, relative to the rest of the ocean floor (e.g., Van Dover, 2000 Zierenberg et al., 2000). Life here ranges in complexity from single cells to higher forms such as tubeworms. The vent ecosystems are unique in many ways, including the fact that the primary producers create biomass not by photosynthesis, as is familiar in more accessible environments, but by chemosynthesis. 

Fig. 28 Nucleophilic ring opening of cyclic dimethylammonium ions [38], Free energies of activation relative to ring-size 6 against cycloalkane strain-energies. Energy units kcal mol"1. (Reproduced with permission from Di Vona et al., 1985)...

Soil respiration (flush of C02) Field chamber Aerobic incubation for >1 week in lab Indicates soil microbial activity relatively simple equipment conducted in a nonstandard laboratory can be determined in field or in laboratory relatively time-consuming dependent upon organic inputs Parkin et al. (1996)... 

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