Polypetide chain

As a polypetide chain is folding into a compact structure, where do you expect the side chains on amino acids such as valine and phenylalanine will wind up Where will the side chains on amino acids such as serine wind up ... 

Beta sheets invariably exhibit a right-handed twist, which is a consequence of non-bonded interactions between the chiral L-amino acid residues in. .. extended polypeptide chains. These interactions tend to give the polypetide chain a right-handed helical twist. 

The other elongation factors, EF-ipy and EF-2, are involved, respectively, in the posthydrolytic exchange of GDP with GTP and in the translocation of peptidyl-tRNA on the ribosome. Of these, EF-2 (95 kDa) has a unique characteristic in the form of a histidine residue at position 715 modified into diphthamide, as a result of which it can be ADP-ribosylated either endogenously or by bacterial toxins such as diphtheria toxin (Riis et al., 1990b). EF-3, which is present in some yeast and fungal species, is a 125 kDa polypetide chain. A unique property of EF-3 is its ability to function with any of the three purine nucleosides (A, G, and I), perhaps to facilitate the interaction of EF-1 a, GTP, and aminoacyl-tRNA. The requirement for EF-3, even in vitro, is an exclusive property of yeast ribosomes. When yeast factors are tested with mammalian ribosomes, EF-3 has no effect (Riis et al., 1990). 

Proteins.— Without entering the subject in detail, it may be recalled that proteins are polypetide chains formed by a number of amino-acids ranging from 51 for bovine insulin to about 6000 for myosin. In each protein there are several chemically-different polar sides the backbone groups of the polypetide chains, and IHNH, and the sidechain groups of the amino-acid radicals,... 

Wool and hair fibres consist mainly of keratin, which consists of polypetide chains bound by salt Unkages between the functional groups of the amino acids (4.127) and by cystine (S—S) linkages (4.128) ... 

Transfer (tRNA) and ribosomal RNA (rRNA) are transcribed and used in protein synthesising processes. Messenger RNA (mRNA) codes the amino-acid sequence of proteins and 95 per cent of the total DNA transcribed is used for this purpose. In prokaryotes a single mRNA molecule may code for a single polypetide or for two or more polypeptide chains. There is a triplet code for each amino-acid 300 ribonucleotides code for a 100 amino-acid sequence. Fig. 5.All shows the relationship between the nucleotide sequence on DNA and RNA and the amino-acid sequence of protein. 

As mentioned above, steroidal assemblies consist of hierarchical structures with supramolecular chirality, leading us to find an analogy on the basis of the concept molecular information and their expression of biopolymers. The information originates from sequential arrangements of a-amino acids. Since it is considered that the steroidal molecules consist of chains of methylene units with various substituents, the concept may be applied to steroidal molecules. Such sequential chains may be considered to hold for other related organic molecules, leading to the idea that chiral methylene chains with various substituents function as universal molecular storage. The methylene chains can be chemically modified to various sequential chains, such as polypetides, polynucleotides, polysaccharides, and ster-... 

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