Component decoder

Table 7.1 Logic s nithesis statistics for the processes in the Decoder component (DECODER-BEHAVIOUR) and Enabler block (SEQUENCE-BEHAVIOUR)...

Most communication systems can be separated into the basic components shown in Fig. 4-la. Figures 4-lb, c, d, e show some specific examples of how particular systems can be separated into these components. There is, of course, considerable flexibility in this separation sometimes it is convenient to consider an antenna as part of the channel, and sometimes as part of the coder or decoder. Here... 

A filter bank is used to decompose the input signal into subsampled spectral components (time/frequency domain). Together with the corresponding filter bank in the decoder it forms an analysis/synthesis system. 

Combinatorial synthesis on solid supports is usually carried out by using either the parallel synthesis (see section 6.2.1) or the Furka split and mix procedures (see section 6.2.2). The precise method and approach adopted when using these methods will depend on the nature of the combinatorial library being produced and also the objectives of the investigating team. However, in all cases it is necessary to determine the structures of the components of the library by either keeping a detailed record of the steps involved in the synthesis or giving beads a label that can be decoded to give the structure of the compound attached to that bead (see section 6.3). The method adopted to identify the components of the library will depend on the nature of the synthesis. 

The steps of initiation occur on the isolated small subunit (30S) of the prokaryotic ribosome. Ribosomes contain two subunits, a 30S and 50S subunit, which associate to form a 70S particle. (The S values refer to the rate at which each component sediments in the ultracentrifuge they don t always add up.) In general, the 30S subunit is mostly involved in the decoding and tRNA-mRNA interaction process, while the 50S subunit is involved in actual peptide bond synthesis. Ribosomal subunits are dissociated prior to the initiation reaction. 

All the spectroscopic approaches applied for structural characterization of mixtures derive from methods originally developed for screening libraries for their biological activities. They include diffusion-ordered spectroscopy [15-18], relaxation-edited spectroscopy [19], isotope-filtered affinity NMR [20] and SAR-by-NMR [21]. These applications will be discussed in the last part of this chapter. As usually most of the components show very similar molecular weight, their spectroscopic parameters, such as relaxation rates or selfdiffusion coefficients, are not very different and application of these methodologies for chemical characterization is not straightforward. An exception is diffusion-edited spectroscopy, which can be a feasible way to analyze the structure of compounds within a mixture without the need of prior separation. This was the case for the analysis of a mixture of five esters (propyl acetate, butyl acetate, ethyl butyrate, isopropyl butyrate and butyl levulinate) [18]. By the combined use of diffusion-edited NMR and 2-D NMR methods such as Total Correlation Spectroscopy (TOCSY), it was possible to elucidate the structure of the components of this mixture. This strategy was called diffusion encoded spectroscopy DECODES. Another example of combination between diffusion-edited spectroscopy and traditional 2-D NMR experiment is the DOSY-NOESY experiment [22]. The use of these experiments have proven to be useful in the identification of compounds from small split and mix synthetic pools. 

RNA molecules are typically much smaller than DNA, and they are more easily hydrolyzed and broken down. RNA commonly serves as a working copy of the nuclear DNA being decoded. Nuclear DNA directs the synthesis of messenger RNA, which leaves the nucleus to serve as a template for the construction of protein molecules in the ribosomes. After it has served its purpose, the messenger RNA is then enzymatically cleaved to its component parts, which become available for assembly into new RNA molecules to direct other syntheses. 

Translator. Aminoacyl-tRNA synthetases are the only component of gene expression that decodes the genetic code. Explain. 

Recently, the use of pulsed-field gradient (PFG) technology to obtain diffusion coefficients of molecules has been demonstrated as a useful technique for mixture analysis (53). Unlike any other 2D experiment, size-resolved or diffusion-resolved NMR assigns the resonances based on the diffusion coefficient for each proton (or other spin) in the molecule and therefore can be used to distinguish resonances arising from different molecules (63-70) (Fig. 22). A method that involves the use of PFG and TOCSY, called diffusion-encoded spectroscopy (DECODES), simplifies mixture analysis by NMR (71). The combination of PFG and TOCSY decodes the spin systems, allowing individual components in complicated mixtures to be assigned. A typical DECODES spectrum obtained in this manner is shown in Fig. 23. The use of TOCSY aids the calculation of the diffusion coefficient and determination of molecular identity. 

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