Separate enzymatic hydrolysis and

Once the SE, LHW, AFEX, and DA pretreatment methods were selected, 24 possible combinations with the six conversion configurations are established. However, based on the pretreatment characteristics, only 16 potential combinations were considered (Eigure 2.12). SE pretreatment is not recommended for implementation with any configuration using solid-liquid separation because of the potential bioethanol inhibition due to high furfural and acetic acid compositions in the fermentation step. The AFEX pretreatment can be combined with separated enzymatic hydrolysis and cofermentation (SHCF) and... 

The mixture of the (R)-HMPC and the (S)-acetate 4 from the enzymatic hydrolysis was esterified with methanesulfonyl choride and triethylamine to afford a mixture of the corresponding (R)-sulfonate 5a and the (S)-acetate 4. The (S)-acetate 4 was unaffected by the sulfonation conditions. The resultant mixture of two esters, 4 and 5a, was hydrolyzed in the presence of a small amount of calcium carbonate. The (R)-sulfonate 5a was converted into the (S)-HMPC 6 as a result of inversion of configuration. On the other hand, the (S)-acetate 4, was hydrolyzed with retention of configuration. Consequently, all of the racemic acetate J3, was converted with maximum efficiency to the desired (S)-HMPC 6, by the sequence enzymatic hydrolysis and sulfonation followed by inversion of the chiral center in (R)-HMPC without separation of the (S)-acetate Similar transformations could also be carried out via nitrate ester intermediate 5b obtained from the reaction of the (R)-HMPC with nitric acid and acetic anhydride. 

Improved protein separation techniques utilizing hquid chromatography and electrophoresis coupled with X-ray diffraction and NMR studies have given insights into the three-dimensional structures of cellulolytic enzymes. This molecular architecture data coupled with DNA sequence information has given clues to the chemical mechanisms of enzymatic hydrolysis and molecular interaction between cellulose and the enzymes. 

The separation,purification and concentration of a thermosensitive bioactive compound from a lysate has been carried out combining UF, ion exchange and RO with significant cost reduction and productivity increase. Enzyme membrane reactors have been used for triglyceride enzymatic hydrolysis and product separation. Thermophi1ic,thermostable enzyme ultrafiltration membrane have been prepared, and used in high temperature lactose hydrolysis. 

The results presented in this paper were only a very preliminary study of pretreatment of maize silage. Trials should be made at lower temperatures to examine if more energy could be saved in the process. It would also be interesting to determine the content of starch and cellulose separately by enzymatic hydrolysis, instead of total glucan as is the case in this study. Also, enzymatic hydrolysis and SSF using low enzyme loadings (of both cellulases and amylases) should be made to fully see the potential of this promising raw material for bioethanol production. 

Vitamin K Vitamin K exhibits an important anti-hemorrhagic activity, which has increased the interest in developing analytical methods to determine its content in foods. The sample preparation includes various steps such as enzymatic hydrolysis and cleanup using SPE cartridges. Normal-phase LC and RP-LC have been used to separate vitamin K in conjunction with UV detection at 270 nm fluorescence detection can be used only after phylloquinone has been converted to the corresponding hydroquinone after electrochemical or chemical reduction. 

FIGURE 4.1 Block diagram of combined enzymatic hydrolysis and two-stage membrane separation (microfiltration (MF) and ultrafiltration) to remove sngars while retaining undigested biomass and enzymes. Reprinted from Andric et al. (2010b) with permission from Elsevier. 

In this paper preparation of antigens and production as well as testing of antibodies raised against different hemicelluloses will be described and examples of their application in chemical mapping of pulp fibres will be presented. Hemicelluloses from different sources were subjected to enzymatic hydrolysis and the oligosaccharides formed were separated and coupled to a carrier protein prior to immunisation of rabbits. 

Unsaturated triglycerides are an important constituent of natural fats and oils. For their analysis a time consuming method is usually employed consisting of enzymatic hydrolysis and chromatographic separation. Fronst et al. (1975) have recently shown that Pr(fod)3 can induce chemical shift differences between the fatty acid residues at the a- and jS-positions of the triglyceride up to 18 carbon atoms along the chain (at 220 MHz). In this way the fatty acid is not only identified, but also its position determined. 

Bioethanol can be produced from the fermentable sugars obtained in the hydrolysis step by bacteria, yeast, or filamentous fungi. In order to prevent the substrate inhibition effects enzymatic hydrolysis and fermentation steps can be combined in a bioprocess called simultaneous saccharification and fermentation (SSF) (Hahn-Hagerdal et al., 2006). At the end of fermentation, ethanol can be purified by distillation and molecular sieves or other separation techniques, which will be ready to be used as a fuel, either neat or blended with gasoline (Hahn-Hagerdal et al., 2006). 

Enzymatic hydrolysis is also used for the preparation of L-amino acids. Racemic D- and L-amino acids and their acyl-derivatives obtained chemically can be resolved enzymatically to yield their natural L-forms. Aminoacylases such as that from Pispergillus OTj e specifically hydrolyze L-enantiomers of acyl-DL-amino acids. The resulting L-amino acid can be separated readily from the unchanged acyl-D form which is racemized and subjected to further hydrolysis. Several L-amino acids, eg, methionine [63-68-3], phenylalanine [63-91-2], tryptophan [73-22-3], and valine [72-18-4] have been manufactured by this process in Japan and production costs have been reduced by 40% through the appHcation of immobilized cell technology (75). Cyclohexane chloride, which is a by-product in nylon manufacture, is chemically converted to DL-amino-S-caprolactam [105-60-2] (23) which is resolved and/or racemized to (24)... 

In this case study, an enzymatic hydrolysis reaction, the racemic ibuprofen ester, i.e. (R)-and (S)-ibuprofen esters in equimolar mixture, undergoes a kinetic resolution in a biphasic enzymatic membrane reactor (EMR). In kinetic resolution, the two enantiomers react at different rates lipase originated from Candida rugosa shows a greater stereopreference towards the (S)-enantiomer. The membrane module consisted of multiple bundles of polymeric hydrophilic hollow fibre. The membrane separated the two immiscible phases, i.e. organic in the shell side and aqueous in the lumen. Racemic substrate in the organic phase reacted with immobilised enzyme on the membrane where the hydrolysis reaction took place, and the product (S)-ibuprofen acid was extracted into the aqueous phase. 

In another approach, the alcohol moiety, formed by an enzymatic hydrolysis of an ester, can act as a nucleophile. In their synthesis of pityol (8-37a), a pheromone of the elm bark beetle, Faber and coworkers [17] used an enzyme-triggered reaction of the diastereomeric mixture of ( )-epoxy ester 8-35 employing an immobilized enzyme preparation (Novo SP 409) or whole lyophilized cells of Rhodococcus erythro-polis NCIMB 11540 (Scheme 8.9). As an intermediate, the enantiopure alcohol 8-36 is formed via kinetic resolution as a mixture ofdiastereomers, which leads to the diastereomeric THF derivatives pityol (8-37a) and 8-37b as a separable mixture with a... 

Simultaneous saccharification and fermentation (SSF) one-stage enzymatic hydrolysis, but the fermentation of pentoses and hexoses takes place in separate process steps. 

Simultaneous saccharification and co-fermentation (SSCF) one-stage enzymatic hydrolysis of cellulose and fermentation of pentoses and hexoses all in one process step. The upstream hydrolysis of the hemicellulose takes place in a separate process step. 

In Sect. 7.3 and 7.4, we have emphasized that an amino group in an ester molecule contributes to increased water solubility and may, in some cases, facilitate enzymatic hydrolysis. In the present section, this argument is further illustrated and is extended to esters containing nonbasic nitrogenated pro-moieties, e.g., amidoalkyl or carbamoylalkyl substituents. Substituents liable to undergo fragmentation (i.e., pro-moieties that will break down during hydrolysis) will be discussed separately in Sect. 8.3. 

One of the first fluorescence-based ee assays uses umbelliferone (14) as the built-in fluorophore and works for several different types of enzymatic reactions 70,86). In an initial investigation, the system was used to monitor the hydrolytic kinetic resolution of chiral acetates (e.g., rac-11) (Fig. 8). It is based on a sequence of two coupled enzymatic steps that converts a pair of enantiomeric alcohols formed by the asymmetric hydrolysis under study (e.g., R - and (5)-12) into a fluorescent product (e.g., 14). In the first step, (R)- and (5)-ll are subjected separately to hydrolysis in reactions catalyzed by a mutant enzyme (lipase or esterase). The goal of the assay is to measure the enantioselectivity of this kinetic resolution. The relative amount of R)- and ( S)-12 produced after a given reaction time is a measure of the enantioselectivity and can be ascertained rapidly, but not directly. 

In the synthesis of A-acetyllactosamin from lactose and A-acetylglucosamine with (3-galactosidase (289,290), the addition of 25 vol% of the water-miscible ionic liquid [MMIM][MeS04] to an aqueous system was found to effectively suppress the side reaction of secondary hydrolysis of the desired product. As a result, the product yield was increased from 30 to 60%. Product separation was improved, and the reuse of the enzymatic catalyst became possible. A kinetics investigation showed that the enzyme activity was not influenced by the presence of the ionic liquids. The enzyme was stable under the conditions employed, allowing its repeated use after filtration with a commercially available ultrafiltration membrane. 

The use of polysaccharide-based CSPs instead of protein-based CSPs often increases the peak efficiency and facilifafes faster separafions. Papini ef al. [159] recently developed a method for the enantioseparation of lorazepam and on a Chiralpak OD-R column and an enzymatic hydrolysis was used to determine the amount of the glucoronide metabolite of lorazepam present. The separation was performed in 7 min with an LOQ of 1 and 10 ng/mL for lorazepam in plasma and urine, respectively. Another relatively fast separation for chiral analysis was published by Lausecker and Eischer [188]. They developed a method for determination of the drug candidate R483 within... 

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