Binding sites, introduction

In contrast to most mRNAs, which become untranslatable after a temperature downshock, cold shock mRNAs possess a mechanism to form the translation initiation complex at low temperature without cold shock ribosomes. A close inspection of the mRNAs of class I cold shock proteins reveal that they are equipped with an extra ribosome-binding site called the downstream box located within the coding region of their transcript [130]. It would be interesting to know whether introduction of this downstream box into a cellular mRNA would convert it into a transcript which can be transcribed immediately after a cold shock. In the case of the cspA mRNA it has been shown that in the absence of the downstream box the initiation complex cannot be formed at low temperature during the accHmation phase [131]. 

It is therefore important to bear in mind the dependency of the carotenoid spectrum upon properties of the environment for in vivo analysis, which is based on the application of optical spectroscopies. This approach is often the only way to study the composition, structure, and biological functions of carotenoids. Spectral sensitivity of xanthophylls to the medium could be a property to use for gaining vital information on their binding sites and dynamics. The next sections will provide a brief introduction to the structure of the environment with which photosynthetic xanthophylls interact—light harvesting antenna complexes (LHC). 

Some recent approaches to orientated immobilization exploited methods of genetic engineering to introduce suitable binding site like a cysteine residue [101]. Mansfeld and Ulbrich-Hofmann introduced cysteine on a thermolysinelike neutral protease from Bacillus stearothermophilus [114]. This approach is especially interesting since it allows the introduction of cystein residues in different positions of the protein molecule and therefore enables one to study the effects of molecule orientation on its biological activity [115]. More information about the oriented immobilization can be found in recent reviews of Turkova [101,110]. 

Moreover, it could be figured out that an effective means to modulate the stereorecognition capabilities of the cinchonan selector motif may be via the carbamate residue. It offers a way of straightforward introduction of bulky alkyl substituents, which may affect the accessibility of active binding sites and/or lead to additional supportive Van der Waals-type interactions. 

After the interaction between the ligand and receptor has reached equilibrium, dissociation kinetics are initiated either by dilution or by the introduction of unlabelled ligand which competes for the receptor binding sites. The purpose, in both cases, is to ensure that once the radiolabelled ligand has dissociated from the receptor, it is not able to reassociate with the receptor. This allows the following reaction to occur in isolation ... 

Affinity maturation of antibodies has been achieved by the introduction of diversity into the V-genes, which then creates diversity within the antigen binding sites. This secondary library is then subjected to a selection that will enrich high affinity variants. More or less random diversity may be introduced by altering variable domain pairings in a process called... 

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