Enzymatic hydrolysis rate

Comparison of Microbial Inhibition and Enzymatic Hydrolysis Rates of Liquid and Solid Fractions Produced from Pretreatment of Biomass with Carbonic Acid and Liquid Hot Water... 

This research quantified the enzymatic digestibility of the solid component and the microbial inhibition of the liquid component of pretreated aspen wood and com stover hydrolysates. Products of liquid hot water and carbonic acid pretreatment were compared. Pretreatment temperatures tested ranged from 180 to 220°C/ and reaction times were varied between 4 and 64 min. Both microbial inhibition rates and enzymatic hydrolysis rates showed no difference between pretreatments containing carbonic acid and those not containing no carbonic acid. Microbial inhibition increased as the reaction severity increased, but only above a midpoint severity parameter of 200°C for 16 min. Both the rates and yields of enzymatic hydrolysis displayed an increase from the lowest tested reaction severity to the highest tested reaction severity. 

The present study investigated the inhibition of Saccharomyces cerevisiae by the liquid hydrolysate and the kinetics of enzymatic hydrolysis of the solid components produced by the pretreatment of aspen wood and corn stover by liquid hot water and hot carbonic acid. Inhibition of yeast was determined by measuring the rate of glucose consumption by yeast growing in hydrolysates produced at various reaction severities. The enzymatic hydrolysis rates of pretreated solids was determined by measuring rates of sugar accumulation of enzyme-digested pretreated solids. 

Both microbial inhibition rates and enzymatic hydrolysis rates showed no differences between pretreatments containing carbonic acid and those not containing carbonic acid. Additionally, when the microbial inhibition and enzymatic hydrolysis rates were tested at varying reaction severities and between different substrates, this remained true. 

Enzymatic hydrolysis rates for different positional and structural esters of lincomycin were determined in dog serum and simulated USP intestinal fluid (75). In general, the hydrolysis rates were faster in simulated intestinal fluid than in dog serum, indicating a higher esterase activity in simulated intestinal fluid. The 2- propionate ester of lincomycin was hydrolyzed slower than the longer chain 2 hexanoate ester, with the greatest difference in rates occuring in simulated intestinal fluid. Sterically hindered esters were hydrolyzed at extremely slow rates. 

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... 

PPSu presents lower crystallinity, crystallization rates, and melting point compared to its homologs PESu and PBSu This in turn results in a polymer with higher enzymatic hydrolysis rates and hence greater biodegradability. On the other hand, retardation in PPSu crystallization is due to its reduced symmetry caused by the propylene units. 

FIGURE 22.3 Enzymatic hydrolysis rate of PLLA films as a function of the inverse of molecular weight (M ). Reprinted with permission from Ref. 12. Copyright 2001, American Chemical Society. 

FIGURE 22.5 Enzymatic hydrolysis rate of PLA stereocopolymer films as functions of the content of L-lactyl unit (Xlla) and of the average sequential length of L-lactyl unit (/l) or D-lactyl unit (/d). The values of /l and /d are calculated by using following equations /l = 2/(1 — Ylla) and = 2/Xlla- Reprinted with permission from Ref. 12. Copyright 2001, American Chemical Society. 

Organophosphorus hydrolase (OPH, EC 3.1.8.1) is a homodimer with a binuclear metal center. OPH has broad substrate specificity and can hydrolyze organophosphate pesticides such as methyl paradiion, ediyl parathion, paraoxon, chlorpyrifos, coumaphos, cyanophos and diazinoa Table I 9,12-14). The enzymatic hydrolysis rates are 40 - 2450 times faster than chemical hydrolysis at pH 7.0 and the enzyme is reported to be stable at ten ratures of up to 4S-S0°C (3). However, hydrolysis rates varied from very fast for phosphotriesters and phosphothiolester pesticides (P-0 bond) such as paraoxon (ken > 3800s ) and coumaphos (kcat = 800s ) to limited hydrolysis for Diazinon (kcat == 176 s ) and fensulfothion (l a, = 67 s ) (14). 

Researchers have found bacterial species, such as Pseudomonas diminuta, Flavobacterium sp. and A. coli, possessing the organophosphate hydrolase enzymes playing an important role in OPs degradation, since the enzymatic hydrolysis rates are 40-2450 times faster than chemical hydrolysis by 0.1 N NaOH at 40 C and the activity of these enzyme are stable at temperatures up to 45-50 °C (Malghani et al. 2009 Richins et al. 1997). 

In another study we correlated enzymatic hydrolysis rates,... 

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