Synthesis representation

To recognize the different levels of representation of biochemical reactions To understand metabolic reaction networks To know the principles of retrosynthetic analysis To understand the disconnection approach To become familiar with synthesis design systems... 

Reaction databases contain a wealth of reactions performed in the laboratory and published in the literature, i.c., in contrast to the transform libraries of synthesis design programs they contain raw, uninterpreted reaction information. In Figure 10,3-41 a schematic representation of a reaction in a reaction database is given. 

Fig. 6. DNA sequence analysis, (a) Simplified methodology for dideoxy sequencing. A primer, 5 -TCTA, hybridized to the template, is used to initiate synthesis by DNA polymerase, (b) Stmcture of 2, 3 -dideoxy CTP. When no 3 -OH functionaUty is available to support addition of another nucleotide to the growing chain, synthesis terminates once this residue is incorporated into the synthetic reaction, (c) Representation of a DNA sequencing gel and the sequence, read from bottom to the top of the gel, gives sequence information in the conventional 5 to 3 direction.

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. 

In this representation the FeCl2 which takes part in the first step of the reaction is not a tme catalyst, but is continuously formed from HQ. and iron. This is a highly exothermic process with a heat of reaction of 546 kj /mol (130 kcal/mol) for the combined charging and reaction steps (50). Despite the complexity of the Bnchamp process, yields of 90—98% are often obtained. One of the major advantages of the Bnchamp process over catalytic hydrogenation is that it can be mn at atmospheric pressure. This eliminates the need for expensive high pressure equipment and makes it practical for use in small batch operations. The Bnchamp process can also be used in the laboratory for the synthesis of amines when catalytic hydrogenation caimot be used (51). 

Fig. 9. Schematic representation of a catalyst for ethylene oxide synthesis (not to scale). The porous support particle consists of microparticles held together...

Figure 8.1 Schematic representation of the REAMEN synthesis problem.

Figure tO.l Schematic representation of the HISEN synthesis problem. 

Figure 12.1 Schematic representation of simultaneous synthesis of MSAs and MEN (Hamad et at, 1996).

Warshawsky and coworkers have recently reported the synthesis of a class of compounds which they call polymeric pseudocrown ethers . A chloromethylated polystyrene matrix is used here as in 6.6.2, but instead of adding a crown to the backbone, a strand of ethyleneoxy units is allowed to react at two different positions on the chain, thus forming a crown. Such systems must necessarily be statistical, and the possibility exists for forming interchain bridges as well as intrachain species. Nevertheless, polymers which could be successfully characterized in a variety of ways were formed. A schematic representation of such structures is illustrated below as compound 30. ... 

Schematic representation uf the main features of the curve of cosmic abundances shown in Fig. 1.1, labelled according tn the various stellar reactions considered to be re.sponsible for the synthesis of the elements. (After E. M. Burbidge et...

Scheme 8.12 Schematic representation of the oxiranyl anion strategy for the synthesis of trans-fused THPs.

Parchmaim et al., 2006 Nieuwe Scheikunde in the Netherlands Driessen Meinema, 2003). For this purpose, we use a synthesis of framewoiks and combine this into a domain-specific curriculum theory (Van Berkel, 2005). VanBerkel s theory is based on the work of Roberts on curriculum emphases, of Schwab on curriculum stractures, of Kuhn on normal science and scientific training and that of Goodlad et al. on cmriculum representations. 

Fig. 6. Schematic representation of synthesis of starch capped copper nanoparticies under microwave conditions...

FIGURE 1 Schematic representation of the use of trifunctional amino acids as monomeric starting materials for the synthesis of pseudopoly-(amino acids), (a) Polymerization via the C terminus and the side chain R. (b) Polymerization via the N terminus and the side chain R. (c) Polymerization via the C terminus and the N terminus. The wavy line symbolizes any suitable nonamide bond. See text for details. ... 

Fig. 16.2 Schematic representation showing the structure features that can be achieved via sait-inciusion synthesis. The covaient oxide is first dissoived (digested) by an ionic soivent in the presence of a reactive moiten haiide sait. Through siow cooiing, crystais containing sait can be grown (see text).

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