Enzymic activity, effect anions

As surfactants are often used in textile processing, it is important to note that anionic or cationic surfactants can inhibit the action of enzymes, as has been reported in the case of cellulases used for the treatment of cotton [140]. Dyes can also inhibit enzyme activity for example, Cl Direct Red 28 has been shown to have a much greater inhibitory effect than Cl Acid Orange 7 [141]. 

There was no detectable activity in the absence of divalent cation. Of the several salts tested, only those with Mg2+, Mn2+, Zn2+, or Co2+ permitted enzymic activity (Table IV). The anion was of no consequence as long as the salt remained soluble, but, as described in the preceding section and documented in Table IV, there were definite pH effects. When more than one of these cations were present together, there was augmentation of activity if both were at less than 0.5 mM however,... 

Hofmeister series — The Hofmeister series (HS) originates from the ranking of anions and cations toward their ability to precipitate a mixture of hen egg white proteins [i]. This protein precipitation can be explained simply in terms of the extent of ions binding to water (i.e., as a salting-out effect). The HS has been shown to have a much more general utility with a broad range of biophysical phenomena, which include the stability and crystallization of biological macromolecules, enzyme activity, DNA-protein interactions, etc. The traditional and extended HS [ii] is shown as... 

The enzyme cholinesterase, effecting the degradation of ACh, consists of two active sites, the anionic and the esteratic site (Figure 9.1). In the first step, ACh is attached to the anionic site and the acetyl group of the ACh molecule is transferred to the amino acid serine. The resulting serine ester is then cleaved hydrolytically and the enzyme is regenerated. ... 

The activity and stability of mushroom tyrosinase in [BMIM] containing ILs were analyzed in detail with respect to the influence of Hofmeister effect of the anions on the catalytic performance of the enzyme and active site structure as well as reaction mechanism [120]. Enzyme activity was in the opposite order to that of the Hofmeister series [BMIM][PFg]>[BMIM][BF ]>[BMIM][MeSO ] which was attributed to the more influential kosmotropic effect of the cation [121]. 

Since disturbed acid phosphatase activity has been associated with pathological conditions, the research has focused on the development of diagnostic methods for detection of activity as a marker for the onset of the disease, and in some extent to the development of inhibitors rather than activators to treat those conditions in which the increase in enzyme activity has a direct effect on the evolution of the disease. In particular, only the development of bisphospho-nate derivatives as inhibitors for tartrate-resistant acid phosphatase found their way to the market for treatment of osteoporosis [41], Typical inhibition of phosphatase activity includes anionic species such as L-(+)-tartrate, phosphate, vanadate, molybdate, and fluoride and neutral molecules such as formaldehyde. Vanadate ion,, is a competitive unspecific inhibitor for acid phosphatases by forming transition state analogs. Other oxoanions such as molybdate and tungstate also show inhibitory effects on... 

Enzyme activity loss because of non-productive adsorption on lignin surface was identified as one of the important factors to decrease enzyme effectiveness, and the effect of surfactants and non-catalytic protein on the enzymatic hydrolysis has been extensively studied to increase the enzymatic hydrolysis of cellulose into fermentable sugars [7, 9 19]. The reported study showed that the non-ionic surfactant poly(oxyethylene)2o-sorbitan-monooleate (Tween 80) enhanced the enzymatic hydrolysis rate and extent of newspaper cellulose by 33 and 14%, respectively [20]. It was also found that 30% more FPU cellulase activity remained in solution, and about three times more recoverable FPU activity could be recycled with the presence of Tween 80. Tween 80 enhanced enzymatic hydrolysis yields for steam-exploded poplar wood by 20% in the simultaneous saccharification and fermentation (SSF) process [21]. Helle et al. [22] reported that hydrolysis yield increased by as much as a factor of 7, whereas enzyme adsorption on cellulose decreased because of the addition of Tween 80. With the presence of poly(oxyethylene)2o-sorbitan-monolaurate (Tween 20) and Tween 80, the conversions of cellulose and xylan in lime-pretreated com stover were increased by 42 and 40%, respectively [23]. Wu and Ju [24] showed that the addition of Tween 20 or Tween 80 to waste newsprint could increase cellulose conversion by about 50% with the saving of cellulase loading of 80%. With the addition of non-ionic, anionic, and cationic surfactants to the hydrolysis of cellulose (Avicel, tissue paper, and reclaimed paper), Ooshima et al. [25] subsequently found that Tween 20 was the most effective for the enhancement of cellulose conversion, and anionic surfactants did not have any effect on cellulose hydrolysis. With the addition of Tween 20 in the SSF process for... 

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