Course content activated processes

The course of biotransformation and the final product properties depend both on the type and composition of the enzyme complex and on the cellulose structure such as the average polymerisation degree and its distribution, crystallinity, capillary system and swelling behaviour as well as the physical-chemical parameters of processes such as ratio enzyme activity to cellulose content, time and temperature reactions. The increased susceptibility of cellulose chains is a result of the modified stmcture and developed intrinsic surface of cellulose obtained by using suitable pre-treatment methods, particularly mechanical processing. ... 

Fig. 1.71. Synopsis of Tict and desorption rates (DR) of the two tests in Fig. 1.63 (1) and Fig. 1.64 (4) and comparison with two other tests (2) carried out as (1) but with activated pressure control at 0.36 mbar and (3) only one tray used (instead of three trays in Fig 1.63), which has been placed at such a slope that the thickness of the product has been 0.5 cm at one side and 0.9 cm at the other. The course of the pressure (see Figs. 1.63 and 1.64) permits quantitative judgment of the SD. The DR data measure, independent of the chosen process data, the amount of desorbed water per hour in % of the solid content. It is visible, that a DR value of 5 %/h in test (4) is reached in 6.2 h, in test (2) in 10.2 h, in test (1) in 13.5 h, but in test (3) the time cannot be estimated. Because of the unequal product thickness, the DR values can change (9.5 h), the desorption process is not uniform for such a product.

Because many cells maintain ATP, ADP, and AMP concentrations at or near the mass action ratio of the adenylate kinase reaction, the cellular content of this enzyme is often quite high. A consequence of such abundance is that, even after extensive purification, many proteins and enzymes contain traces of adenylate kinase activity. The presence of this kinase can confound the quantitative analysis of processes that either require ADP or are carried out in the presence of both ATP and AMP. Furthermore, the equilibrium of any reaction producing ADP may be altered if adenylate kinase activity is present. To minimize the effect of adenylate kinase, one can utilize the bisubstrate geometrical analogues Ap4A and ApsA to occupy simultaneously both substrate binding pockets of this kinase . Typical inhibitory concentrations are 0.4 and 0.2 mM, respectively. Of course, as is the case for the use of any inhibitor, one must always determine whether Ap4A or ApsA has a direct effect on a particular reaction under examination. For example. Powers et al studied the effect of a series of o ,co-di-(adenosine 5 )-polyphosphates (e.g., ApnA, where n =... 

A specific feature of most heterogeneous catalysts is obviously the diver sity of simultaneously operating active centers, which differ from one another by their physicochemical properties (activity, etc.) and, as a conse quence, the feasibility of diversified routes of catalytic transformations. In a majority of homogeneous, heterogeneous, and enzymatic processes, the total number of active centers is preserved in the course of the reaction and, therefore, a balance exists for the amount of aU of the species in the active center. There are, however, exceptions to the rule—for example, one specific acid catalysis where the number of active centers depends on the content of H30 ions, which is controlled by the pH of the medium. 

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