Link sequences

Sequence variance portal Human Genome Variation Society (HGVS) http //www.genomic.unimelb.edu.au/mdi/ Links sequence variation databases... 

Conserved histidine-containing sequences were recognised at an early stage as the probable heme-linked sequences in classical plant peroxidases (Welinder and Mazza, 1977). Similar sequences were later found in CCP (Ihkio et al., 1980) and recently in... 

DNA consists of a chemically linked sequence of four nucleotides. Each trinucleotide sequence is coded for a corresponding amino acid. Because of the codon degeneracy, some amino acids are coded by more than one triplet. Since a library of random peptides should contain all the possible sequences, the corresponding DNA fragments would have to be degenerated oligonucleotides, which are chemically synthesized as a mixture of sequences. 

To explain this precision and integration of linked sequences of enzyme function, several regulatory models are currently being evaluated by workers in this field (Hochachka et al.,... 

Much like temperature, many industrial applications of enzymes require activity in the presence of organic solvents. Interestingly, Burton et al.118 have pointed out that thermostability and tolerance of organic solvents are characteristics that are often linked sequence and structural modifications that improve activity to one denaturing influence often also improve tolerance to others. Unfortunately, enzymes have generally evolved to function in aqueous media solvents are believed to denature and inactivate enzymes by exclusion of water from critical structural or functional components. Thus, many enzymes cannot tolerate common bioprocess conditions and techniques such as directed evolution must be used to improve their stability. 

Actually, these sequences are not seen (for the same reason to avoid transferring large data sets through the web), but they can be checked by clicking on the link sequences. ... 

There are two typologies of linking flexible assembly systems permanent and flex-link sequences. Linking with a permanent linking sequence means that each assembly system is linked in a set sequence to each other, such as with longitudinal transfer systems (see Figure 7). The permanent linking sequence allows these assembly systems to execute only a smaller number of assembly tasks with different assembly sequences. They are therefore suitable for the automated assembly of variants and types with comparable assembly sequences and several similar products or components with comparable assembly sequences. 

Particularly for small annual workpiece amounts, it is economically necessary to assemble several different products or components in one flexible automated assembly system in order to maintain a high level of system utilization. Because sometimes very different assembly processes must be realized, a linking structure (flex-link sequence), independent from certain assembly processes, is necessary. Assembly systems of this type are able to meet the increasing demands for more flexibility. 

Variations in cross-linking occur by two means the frequency of linkage and the nature of the link sequence. It is not clear how the first is really determined. In some peptidoglycans only a proportion of the muramyl residues are substituted by peptide chains and so can be involved in cross links. Where peptide chains are present the removal of terminal D-alanine by carboxy-peptidase would prevent transpeptidation and cross-linkage. 

Wall peptidoglycan syntheis in Gram-positive bacteria is susceptible to inhibition with tunicamycin, seemingly by more than one mechanism. Both link sequences and peptidoglycan chain synthesis are affected and the predominant antibacterial action probably differs somewhat between species. 

In all cases, save the formation of the link sequence in the bacterial peptidoglycan, it is a transfer of A/-acetylglucosamine (as its 1-phospho derivative) to a phospholipid acceptor that is blocked by tunicamycin. 

Figure 4.15 The Biosynthesis of Some A -linked Sequences, as Derived from the Experiments of Beyer etaL (1979). Note that enzyme specificity defines singular routes to many structures and that some structures are forbidden. For details see the text.

For some polysaccharides, such as keratan sulphate, the linkage sequences seem to have the same sfructixres as the oligosaccharides of conventional glycoproteins and the pathways of their synthesis are presumably the same. Hence mucin-type or complex-type chains can act as link sequences and so dolichol can be involved in some forms of link production. Some other polysaccharides, such as heparin, are attached to sequences that have no known counterpart in typical glycoprotein assembly. 

When these chains are attached to a core protein or proteins they form gigantic glycoproteins termed proteoglycans . They tend to have the link sequence Ser-Xyl.Gal.Gal.GlcA-, except that keratan sulphate can be linked by conventional glycoprotein link sequences and no proteoglycan of hyaluronic acid is known. 

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