Inactivation immobilization

The phenomenon, that a little excess amount of short-chain alcohols inactivates immobilized C. antarctica lipase but their overly excessive amounts do not, has not yet been clarified. However, because it is well known that lipase is active and very stable in water-immiscible organic solvents (Zaks and Klibanov, 1984), this fact may be explained the enzyme has bound water which it needs for the expression of its activity and which affects the maintenance of its structure. The structure is not maintained in the mixture including a small excessive amount of EtOH, but is strengthened in the mixture including large excessive amounts of EtOH owing to removal of bound water which does not participate in the expression of the activity. 

Several methods have been developed for the patterning of biomolecules or locally modulating their activity on surfaces [10]. Local generation of bromine or chlorine can be used to inactivate immobilized enzymes. The system studied... 

The substrate, L-aspartate, is produced from fumarate by an enzyme system involving aspartase, as described in the section on L-aspartate. To produce L-alanine directly from fumarate, the L-alanine-producing column was connected in tandem to an L-aspartate-producing column. In this tandem column system, side reactions caused by fumarase in Escherichia coli and alanine racemase in P. dacunhae reduced the yield. Then, both bacterial cells were separately treated with high temperature and low pH, respectively, and the enzymes responsible for the side reactions were inactivated. Immobilization of these two kinds of bacterial cells with K-carrageenan resulted in the production of L-alanine in a single reactor without the production of the side products, malate and o-alanine (Takamatsu et al. 1982 Chibata et al. 1986b). 

Fig. 24. Kinetics of add inactivation of a-amylase (Bac. subtilis) in solution (/, 2) and immobilized on Biocarb (3) 1) pH 2 2) and 3) pH 4. A/A0 is the value of relative enzymatic activity (compared to the initial activity A0 before inactivation), substrate — starch...

Fig. 25. Reactivation of inactivated of 1) a-amylase at different pH values of the solution, 2) oc-amylase immobilized in Biocarb...

The reactivation of enzymes (after their partial inactivation in an acid medium) upon passing into a medium of pH 8 is also of great importance for oral use (Fig. 25). Enzymes immobilized in crosslinked polyelectrolytes are characterized by a structural memory even after considerable inactivation. Under changed conditions, this leads to a considerable or almost complete reactivation of the enzyme, whereas in the reactivation of a free enzyme in solution under similar conditions the enzymatic activity is restored on a lower level. 

The most limiting factor for enzymatic PAC production is the inactivation of PDC by the toxic substrate benzaldehyde. The rate of PDC deactivation follows a first order dependency on benzaldehyde concentration and reaction time [8]. Various strategies have been developed to minimize PDC exposure to benzaldehyde including fed-batch operation, immobilization of PDC for continuous operation and more recently an enzymatic aqueous/octanol two-phase process [5,9,10] in which benzaldehyde is continuously fed from the octanol to the enzyme in the aqueous phase. The present study aims at optimal feeding of benzaldehyde in an aqueous batch system. 

All soil metabolic proce.sses are driven by enzymes. The main sources of enzymes in soil are roots, animals, and microorganisms the last are considered to be the most important (49). Once enzymes are produced and excreted from microbial cells or from root cells, they face harsh conditions most may be rapidly decomposed by organisms (50), part may be adsorbed onto soil organomineral colloids and possibly protected against microbial degradation (51), and a minor portion may stand active in soil solution (52). The fraction of extracellular enzyme activity of soil, which is not denaturated and/or inactivated through interactions with soil fabric (51), is called naturally stabilized or immobilized. Moreover, it has been hypothesized that immobilized enzymes have a peculiar behavior, for they might not require cofactors for their catalysis. 

Phytostabilization (also known as in-place inactivation or phytoimmobilization) is the use of certain plant species to immobilize contaminants in the soil through absorption and accumulation by roots, adsorption onto roots, or precipitation, complexation, and metal valence reduction within the root zone. The following three mechanisms determine the fate of the contaminants within the phytostabilization process46 ... 

Pure Ti02 was recently reported to be active in the disinfection of water contaminated by spores of the type Fusarium solani [142], Bacillus anthracis [143], or Cryptosporidium parvum oocysts [144], or when supported as nanocomposites on zeolite H(i for E. coli deactivation [145], and it found applications in water treatment as a replacement for chlorine. Ag-Ti02 immobilized systems were used for inactivation of bacteria, coupling the visible light response of the system and the strong bactericidal effect of Ag [146]. Silver was deposited on hydroxyapatite to form nanocomposites with a high capacity for bacterial adsorption and inactivation [147], or used for airborne bacterial remediation in indoor air [148],... 

It is extraordinary that eIF4A was found among a number of other proteins bound to the PatA beads without the knowledge of how much PatA is attached to the beads and, more importantly, whether such attachment would lead to inactivation of PatA. In retrospect, it is fortuitous that the amino group used to immobilize PatA onto solid phase can indeed tolerate further chemical modifications without a significant loss of activity. 

Summarizing the results of many investigations, monosaccharides and such derivatives as D-mannitol and D-glucitol are rather weak acceptors. Disaccharides, including such acceptor products as isomaltose, are much better acceptors, except for certain molecules, for instance leucrose, which is not an acceptor.29,46,47 The decrease of enzyme activity with time has been described in terms of a first-order reaction. The inactivation parameters have been calculated for the immobilized enzyme. The inactivation constants kd were 0.0135 (1/d) when maltose was the acceptor (stabilizing), and 0.029 (1/d) when fructose was the acceptor.38... 

However, an important problem arises during the peroxidative removal of phenols from aqueous solutions PX is inactivated by free radicals, as well as by oligomeric and polymeric products formed in the reaction, which attach themselves to the enzyme (Nazari and others 2007). This suicide peroxide inactivation has been shown to reduce the sensitivity and efficiency of PX. Several techniques have been introduced to reduce the extent of suicide inactivation and to improve the lifetime of the active enzyme, such as immobilization. Moreover, Nazari and others (2007) reported a mechanism to prevent and control the suicide peroxide inactivation of horseradish PX by means of the activation and stabilization effects of Ni2+ ion, which was found to be useful in processes such as phenol removal and peroxidative conversion of reducing substrates, in which a high concentration of hydrogen peroxide may lead to irreversible enzyme inactivation. 

We have evidence that the female herself controls the mechanism by which one set of sperm is favored over the other. If females are anesthetized so as to inactivate their muscles, including presumably the many pumping muscles of their reproductive organs, the normal routing of sperm is inhibited. The anesthesia does not immobilize the sperm, indicating that it is not the sperm themselves that are in control of their fate (26). The reproductive system of female Utetheisa is a complex labyrinth of ducts and chambers. While we do not know precisely how... 

Sensing of encapsulation-induced physiological stress will help in the devising of synthesis procedures that will minimize cell inactivation during immobilization. 

Already immobilized enzyme monolayers can be inactivated with iodoa-cetate, and active monolayers can be attached de novo on top of the inactivated layers. The use of these procedures allows the construction of a large variety of structures whose spatial order can be investigated as detailed in the next section. 

The enzyme immobilized in a film can be inactivated by oxidizing potentials. 

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