Stereospecific activity

Furthermore, by in vitro experiments, it has been verified that stereospecific activation of alprenoxime is organ-specific, occurring in the eye and not systemically. When administered locally to rabbits, marked decreases in intra-ocular pressure were observed, whereas oral administration elicited almost no cardiac effects. Such ketoximes represent promising chemical delivery systems in the treatment of glaucoma However, a major limitation is their poor stability in solution, seemingly due to hydrolysis of the oxime function. 

Furukawa and his coworkers (20) considered the stereospecifically active catalyst speties of the polymerization catalyzed by the metal alkyl MR to be the metal alkoxide derived easily by the reaction with monomeric acetaldehyde. 

Most of the hormonal activities of thyroid hormones result from the binding of T3 to chromatin-associated nuclear receptors. Recent evidence suggests that, in several cells, translocation of T3 and T4 from plasma to the intracellular compartment is accomplished by a receptor-mediated, limited capacity, active transport system37. In hepatocytes, it has also been shown that an energy-dependent stereospecific active transport system is involved in the translocation of T3 from the cytosol into the nucleus38,39. 

The stereospecific activity of the catalysts is given by the possibilities of the space arrangement of the aletane transition form in scheme (162). According to Ivin et al., insertions into the simple metal—carbon bond are an exception rather than a rule [303]. 

Ahmed, S. Imai, T. Yoshigae, Y. Otagiri, M. Stereospecific activity and nature of metabolizing esterases for propranolol prodrug in hairless mouse skin, liver and plasma. Life Sci. 1997, 61 (19), 1879-1887. 

Fig. 8. 1,6-Anhydro ring opening polymerization Stereospecific activated chain...

Lu T, VanRollins M, Lee HC (2002) Stereospecific activation of cardiac ATP-sensitive K(+) channels by epoxyeicosatrienoic acids a structural determinant study. Mol Pharmacol 62 1076-1083... 

Kashiwa found that suitable amounts of ethenebenzoate increased the yield of isotactic polymers at the same time, the production of atactic polymer is strongly decreased. So the aromatic ester simultaneously acts as a poison of the aspecific sites and as an activator of the isospecific sites It is reasonable to assume that a highly active and stereospecific catalyst can be obtained by selectively using only the stereospecifically active... 

A comparison of these scales with Taft s induction constants a and Taft s steric constants for different alkyl groups leads to the conclusion that both electronic and steric factors influence the doublebond activity in stereospecific catalysis but that steric factors seem to be more important. An especially significant decrease in the olefin activity was found for olefins branched vicinally to the double bond (3-methyl-pentene-1,3-methylbutene-l, vinylcyclohexane, styrene). This is protebly connected with the space limitations for monomer coordination in the stereospecific active sites (IS, 16). 

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