Inductive synthesis

A detailed study (231-233) reveals that most probably the protonated, adsorbed alcaloid offers the chiral template for the inductive synthesis. It participates as a proton donor in a fast preestablished 2e /2H+ equilibrium followed by a final desorptive step that establishes and stabilizes the acquired molecular configuration. Figure 34 describes the reaction model—albeit somewhat naively and oversimplified. 

In an inducible enzyme system, the R. is inactive in the presence of the effector (inducer) binding to the inducer apparently changes the conformation of the R., so that it no longer binds to the operator (see Enzyme induction). Synthesis of mRNA can therefore proceed only when the inducer is present. In enzyme repression, the situation is revets R. is activated by a corepressor (the endproduct of a biosynthetic pathway, e.g. an amino acid) so that it can bind to the operator. In this case, synthesis of mRNA proceeds only in the absence of corepressor (see Enzyme repression). See also Derepression. 

Most of the mentioned problems can, however, be overcome by addition of small amount of seed crystals (ZSM-5, silicalite-1) in the TPA+-free reaction mixture [6, 27, 35, 38, 40, 45, 50], Seed induction synthesis is a well developed strategy which could not only shorten the duration of synthesis, but also control the product properties [51] addition of seed crystals results in the formation of zeolite ZSM-5 with high degree of crystallinity and a narrow size distribution at short synthesis times [38,40]. Such method has been used for the synthesis of zeolites with various framework topologies [52]. Recently, small sized zeolites were obtained fastly, using this approach [53]. This method, although old, is still under developing. 

F. Bergadano and D. Gunetti. Inductive synthesis of logic programs and inductive logic programming. In [Deville 94], pp. 45-56. 

K. P. Jantke and U. Goldammer. Inductive synthesis of rewrite rules as program synthesis. In [Clement and Lau 92], pp. 65-68. 

In Chapter 3, we survey the use of inductive inference in automatic programming. Specifications by examples are concise and natural, but are usually also incomplete and ambiguous, due to the insufficient expressive power of examples. As inductive inference is much less known than deductive inference, we first survey this field. Inductive synthesis from specifications by examples can be classified into trace-based synthesis and model-based synthesis. We survey the achievements of inductive synthesis of LISP functions and Prolog predicates. 

There have been several reviews of asymmetric synthesis via chiral organoboranes (6,8,378,382,467—472). Asymmetric induction in the hydroboration reaction may result from the chiraHty present in the olefin (asymmetric substrate), in the reagent (asymmetric hydroboration), or in the catalyst (catalytic asymmetric hydroboration). 

Pig. 3. Representation of promoter sites on the pro-enkephalin gene. The numbers represent the distance in nucleotides from the pro-enkephalin initiation codon the arrow indicates the direction of transcription. The TATA promoter box occurs immediately before the pro-enkephalin initiation site the AP-2 site, which binds immediate-early gene products, is 70 nucleotides upstream, and the CRE site, which binds a regulatory protein involved in cAMP induction of mRNA synthesis, is 107 nucleotides upstream from the initiation codon. The expanded section shows that the CRE site actually consists of two elements, ENKCRE-1 and ENKCRE-2, which separately confer cAMP sensitivity to pro-enkephalin mRNA synthesis. 

Induction of Asymmetry by Amino Acids. No fewer than sis types of reactions can be carried out with yields of 75—100% usiag amino acid catalysts, ie, catalytic hydrogenation, iatramolecular aldol cyclizations, cyanhydrin synthesis, alkylation of carbonyl compounds, hydrosdylation, and epoxidations (91). 

Teratogenic effects have been noted with 2- and 4-aminophenol in the hamster, but 3-aminophenol was without effect in the hamster and rat (129,130). 4-Aminophenol is known to inhibit DNA synthesis and alter DNA stmcture in human lymphoblasts (131,132) and is mutagenic in mouse micronuclei tests (133). The aminophenols have been shown to be genotoxic, as evidenced by the induction of sister chromatid exchanges (134,135), but they also exert a protective effect against DNA interaction with other noxious chemicals (136). After assessment of available data a recent report stated that the aminophenols were safe as cosmetic ingredients in their present uses and concentrations (137). 

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