Sequential operation, structural

From a point of view of industrial protein production the number of sequential operations necessary to achieve the desired purity of a protein contributes significantly to the overall costs of the downstream process. This is on one hand due to the capital investment and amount of consumables needed for each step as well as to the individual time requirements of each operation, as labour costs are a very important factor in the calculation of process economics. Secondly the overall yield of the purification is reduced with each additional process step, originating from its inherent loss of product. Furthermore, fast primary recovery should separate the protein of interest from process conditions detrimental to its structural stability, e.g. proteases, glycosidases, or oxidizing conditions. As the performance of the purification process, expressed by its overall yield, operation time, and capital cost may contribute to up to 80% of the total production costs [2], it is evident, that a reduction of the number of sequential steps in a purification protocol may be the key to the economic success of a potential protein product [3],... 

Parameter settings parameters can be set individually depending on weighting some edit operations more or less. A series of tests has brought three data sets to obtain alignments based on sequential or structural properties or on a mixture on both. These data sets are shown in Fig. 3. 

Studies on nonribosomal peptide formation by multienzymes have demonstrated the modular organization of these systems. As in the case of polyketide formation, the linear arrangements of modules determine their sequential operation. Their various modes of integration, however, are still not understood. It is evident that substrate-activating sites introducing amino and imino acids as well as hydroxy acids have different specificities. Thus, variations in the structures of side chains are easily accomplished, and these exceed the variability of polyketide systems in this respect. Work is in progress to make use of such systems for structure-function studies in the analysis of natural products and in the biosynthesis of new products. Future efforts will be directed to linking system variations to various selection processes. 

Square nodes in the ANFIS structure denote parameter sets of the membership functions of the TSK fuzzy system. Circular nodes are static/non-modifiable and perform operations such as product or max/min calculations. A hybrid learning rule is used to accelerate parameter adaption. This uses sequential least squares in the forward pass to identify consequent parameters, and back-propagation in the backward pass to establish the premise parameters. 

In the ion trap technology, ions are captured in three-dimensional electric fields. The continuous beam of ions fills the trap up to the limit of their space charge. When additional electric fields are applied, ions are ejected sequentially and detected. Accumulation of ions in the trap results in high sensitivity for these instruments. The trap can be operated in MS and MS/MS modes. In the latter, the ions of interest are maintained in the trap, whereas the other ions are excluded. Sequential fragmentation steps can be performed to generate MSn spectra, highly valuable for structural characterization studies. 

As many metabolic pathways are branched, feedback inhibition must allow the synthesis of one product of a branched pathway to proceed even when another is present in excess. Here a process of sequential feedback inhibition may operate where the end-product of one branch of a pathway will inhibit the first enzyme after the branchpoint (the conversion of C to D or C to E in Fig. lb). When this branchpoint intermediate builds up, it in turn inhibits the first committed step of the whole pathway (conversion of A to B in Fig. lb). Since the end-product of a metabolic pathway involving multiple enzyme reactions is unlikely to resemble the starting compound structurally, the end-product will bind to the enzyme at the control point at a site other than the active site. Such enzymes are always allosteric enzymes. 

In the chemical industries, the pretreatment of educts, their chemical conversion into valuable products, and the purification of resulting product mixtures in downstream processes are carried out traditionally in sequentially structured trains of unit operations. In many cases, the performance of this classical chemical process structure can be significantly improved by an integrative coupling of different process units. 

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