Specificity primary structural

In both bacteria and eucarya the susceptibility to certain ribosome-targeted inhibitors correlates with specific primary structural features of rR24A, or with features of the ribosomal domain that acts as the antibiotic binding sites. Firstly, resistance to specific ribosome-directed drugs is conferred by single-base changes within phylogenetically... 

Because the tertiary structure of a globular protein is delicately held together by weak intramolecular attractions, a modest change in temperature or pH is often enough to disrupt that structure and cause the protein to become denatured. Denaturation occurs under such mild conditions that the primary structure remains intact but the tertiary structure unfolds from a specific globular shape to a randomly looped chain (Figure 26.7). 

The structural varieties of hemicelluloses offer a number of possibilities for specific chemical, physical, and enzymic modifications. Future advancements will be based on the synthesis of hemicellulose-based polymers with new functionalities and with a well-defined and preset primary structure both on the level of the repeating imit and the polymer chain. Hemicelluloses have also started to be attractive to synthetic polymer chemists as... 

In nature, there are 20 amino acids available for incorporation into the protein chain. They are arranged in a specific and characteristic sequence along the molecule. This sequence is generally referred to as the primary structure of the protein. Also part of the primary structure is the relative molar mass of the macromolecule. 

A primary structure represents a polypeptide as a simple linear string of amino acids. Actually, within long polypeptides, certain sections fold into sheets or twist into coils. These regions with specific structural characteristics constitute the secondary structure of the protein. Figures 13-37 and 13-38 show the two most common secondary structures. 

In 1990, work was started to characterize the human genome which had been shown to consist of about 3 billion base pairs. The final result was announced in the year 2000. All of the chromosomes have been characterized. The human genome has been shown to contain some 30,000 genes (which are sections of the chromosome which code for specific proteins). Each cell produces the t T)e of proteins needed for it to function. The function of mRNA is to transfer information from the DNA. so as is to fix the limits of the protein needed. The vast majority of the proteins found in living organisms are composed of only 20 different kinds of amino acids, repeated many times and strung together in a particular order. Each type of protein has its own unique sequence of amino acids. This sequence, known as its primary structure, actually... 

His residues in the peptide sequence are fundamental for Ni11 ion interactions with peptides. When the His residue is relatively distant from the N terminus, it may compete as a primary ligation site with the N-terminal amino nitrogen. However, even the higher number of His residues inserted inside the peptide sequence may be not able to compete with the albumin-like N terminus, unless the specific peptide structure is established. 

Cholinesterases secreted by parasitic nematodes of (predominantly) the alimentary tract or other mucosal tissues are authentic AChEs when analysed by substrate specificity, inhibitor sensitivities and primary structure. In the first two respects, they resemble vertebrate AChEs, whereas somatic (and therefore presumably neuronal) enzymes of nematodes analysed to... 

Arias. Primary structure and functional expression of a cDNA encoding the bile canalicular, purine-specific Na(+)-nucleoside cotransporter./. 

Disulfide bridges are, of course, true covalent bonds (between the sulfurs of two cysteine side chains) and are thus considered part of the primary structure of a protein by most definitions. Experimentally they also belong there, since they can be determined as part of, or an extension of, an amino acid sequence determination. However, proteins normally can fold up correctly without or before disulfide formation, and those SS links appear to influence the structure more in the manner of secondary-structural elements, by providing local specificity and stabilization. Therefore, it seems appropriate to consider them here along with the other basic elements making up three-dimensional protein structure. 

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