that are present in mRNA and contain the information of proteins are known as exons. Thus, HnRNA produced after transcription is quite longer than the mRNA. Most of the extra nucleotide sequences, including introns, are cleaved by snurp. Moreover, after removal of the extra nucleotides from the 3′ end of the HnRNA, poly A tail is added that is required for the stability of the mRNA. Similarly, after removal of extra nucleotides from the 5′ end, a cap of 7-methyl guanosine (7mG) is added that is required for the translation process. The production and processing of HnRNA occurs in the nucleus from where it escapes into the cytoplasm through nuclear pores for the translation process (Fig 8.11 and 8.12).

This step is believed to be facilitated by unidentified proteins.

Sonication-Assisted Library Synthesis of Oxazolidinone-Carbohydrate Conjugates.

Design, Synthesis, and Antibody Binding Study.

The other approach is to introduce backbone protecting groups which will prevent the formation of hydrogen bonds. Such protection is made by the introduction of the Hmb group on the αnitrogen [53]. It has been shown that the presence of a Hmb unit every 6-7 residues is sufficient to disrupt the peptide aggregation [54]. The Hmb protected amino acid is introduced under the form of N,O-bis-Fmoc-N-(2hydroxy-4-methoxybenzyl) derivative, the O-Fmoc protection being cleaved during the following piperidine treatment. At the end of the synthesis the Hmb group is cleaved in the final TFA cleavage.

Fig. 8.16 Translation process of protein synthesis in prokaryotes.

Two approaches can be used to disrupt the aggregation; the first one consists in modifying the environment in which the synthesis is made and to introduce elements known to disrupt hydrogen bonds; among them we list:

Photovoltaic Properties of New Cyanine-Naphthalimide Dyads Synthesized by 'Click' Chemistry.

Synthesis of Cyclo-PMMA via Click Chemistry Combined with ATRP.

To complete (+)DNA strand synthesis, an intramolecular transfer is required to give the (+)DNA strand access to the uncopied portion of the (-)DNA strand.

Synthesis of Lanthanide(III) Chelates by Using 'Click' Chemistry.

A special paragraph will be dedicated to the problems caused by peptide aggregation in the course of the synthesis. This phenomenon is a major cause of trouble as it is difficult to predict, is sequence dependent and no universal solution has been found up to now.

Synthesis of Ferrocene-containing Polyacetylenes by Click Chemistry.

A long-term oral anticoagulant therapy results in suppression of the synthesis of both vitamin K-dependent coagulation factors and Protein C, but the production of the coagulant and anticoagulant proteins is well-balanced.

Copper-Catalyzed Synthesis of -Sulfonyl-1,2,3-Triazoles: Controlling Selectivity.

Synthesis of New Substituted Lactones by "Click" Chemistry.

R.; Duddu, R.; Yang, K.; Damavarapu, R.; Gelber, N.; Surapaneni, R.; Gilardi, R., Preparation of cage molecule based polyazido core units for dendrimer synthesis.

Synthesis of Saccharide-Terminated Poly(ε-caprolactone) via Michael Addition and 'Click' Chemistry.

Estrogenic Analogues Synthesized by Click Chemistry.

Sequence-independent RNA cleavages generate the primers for plus strand DNA synthesis in hepatitis B viruses: implications for other reverse transcribing elements.

The Potential of Cycloaddition Reactions in the Synthesis of Dendritic Polymers.

Aziridines in Parallel- and Solid-Phase Synthesis.

Better results will be obtained by repeating a coupling with fresh reagents (and changing coupling parameters if a low conversion was obtained) rather than by prolonging the reaction. Generally, coupling protocols may be changed in the course of a synthesis, especially when optimizing an SPPS.