Sequences in synthetic

Yamamoto, S., Yamamoto, T., Kataoka, T., Kuramoto, E., Yano, O. and Tokunaga, T. (1992) Unique palindromic sequences in synthetic oligonucleotides are required to induce IFN and augment IFN-mediated natural killer activity. J. Immunol., 148, 4072 1076. 

Although recent years have witnessed an impressive confluence of experiments and statistical theories, presently there is no comprehensive understanding of the interrelation between chemical sequences in synthetic copolymers and the conditions of synthesis. One has merely to glance at recent literature in polymer science and biophysics to realize that the problem of sequence-property relationship is by no means entirely solved. As always, in these circumstances, an alternative to analytical theories is computer simulations, which are designed to obtain a numerical answer without knowledge of an analytical solution. 

If alternating hydrophilic and hydrophobic amino acid sequences in synthetic peptides are at the right distances in space, the molecule coils with the hydrophobic amino acids on the inside of each coil and the hydrophilic ones to the outside. There are still, however, many stmctural mysteries the interior of many protein stmctures with myriads of side-chains, and the way in which metal ions can stabilize three-dimensional stmctures, have been likened to a terra incognita. 

Simha, R Polymerization kinetics and sequences in synthetic polynucleotides, Proc. Inti. Symp. Macromolecular Chem., Moscow (1960). 

Aromatization of indolines is important in completing synthetic sequences in which the directive effects of the indoline ring have been used to achieve selective carbocyclic substitution[l]. Several methods for aromatization have been developed and some of these are illustrated in Table 15.2. A range of reagents is represented. One type of procedure represents use of oxidants which are known to convert amines to imines. Aromatization then provides the indole. Such reagents must not subsequently oxidize the indole. Mereuric acetate (Entry 1) is known to oxidize other types of amines and presumably reacts by an oxidative deprotonation ot- to the complexed nitrogen. 

Metha.nol-to-Ga.soline, The most significant development in synthetic fuels technology since the discovery of the Fischer-Tropsch process is the Mobil methanol-to-gasoline (MTG) process (47—49). Methanol is efftcientiy transformed into C2—C q hydrocarbons in a reaction catalyzed by the synthetic zeoHte ZSM-5 (50—52). The MTG reaction path is presented in Figure 5 (47). The reaction sequence can be summarized as... 

Linker-Scanning Mutagenesis. Using linker-scanning mutagenesis (24) small sequences of DNA are removed and replaced with a synthetic restriction fragment or linker. This technique is commonly used in analysis of promoters and other control sequences in DNA, while preserving the spatial relationship between the sequences. 

It is a common experience in synthetic chemistry that a truly optimal ordering of a synthetic route may not be possible in the planning stage, but may have to determined experimentally. The precise information necessary for the complete and unambiguous evaluation of each step in a possible synthesis is hardly ever available. Nonetheless it is clearly wise to try to optimize a synthetic plan on the basis of available information before the experimental approach begins. Such an effort may suggest certain preliminary or "model" experiments that can be helpful in the choice or refinement of a synthetic plan. It is also obviously desirable to devise and consider alternate or bypass paths for each problematic step of a synthetic sequence. 

While esters do not usually react with enamines and can, in fact, be substituents in the azeotropic preparation of enamines, they can be used in acylation reactions when these involve intramolecular cyclizations. Such reactions have been observed even at room temperature when they lead to the formation of five- and six-membered vinylogous lactams (362). Applications to precursors for azasteroids (40S) and alkaloids (309,406) are key steps in synthetic sequences. 

If methvloctvldichlorsilane is used as the reagent in a sequence of synthetic steps, an oligomeric phase can be built up on the surface. 

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