Lipase adsorbed

The diameter of lipase globules is generally around 50A. Pedersen and Hansen (1994) discovered that lipases adsorb well to silica, if the adsorption is carried out... 

As expected, the amount of lipase adsorbed in hydrogel fibers was much higher than that in the cast films with the same polymer composition because of the much larger specific surface of the fibers. For example, when the adsorption was performed in a pH 7 buffer, the amount of lipase immobilized in the cast film (3.5 COOH/OH molar ratio) was only about 58% of that in the hydrogel fibers of the same polymer composition. 

Figure 5, Kinetics of catalytic hydrolysis (30PC, pH 8,5) of olive oil by (a) crude lipase (b) lipases adsorbed by PAA/PVA hydrogel fibers (COOH/OH molar ratio = 5. the lipase adsorption was conducted in pH 4 buffer solution).

Psychrotrophs, which can dominant the microflora of refrigerated milk, are a potentially important source of potent lipases in cheese. Cousins et al. (1977) considered that active lipase would be present in cheese if psychrotroph numbers exceed 10 CFU ml K Many psychrotroph lipases are heat stable and thus may cause rancidity in cheese over the course of a long ripening period. The subject of psychrotroph enzymes in cheese was discussed by Mottar (1989). Unlike psychrotroph proteinases, which are largely water-soluble and are lost in the whey, psychrotroph lipases adsorb onto the fat globules and are therefore concentrated in the cheese. 

The effect of the wetting characteristics of the membrane in the hydrolytic activity of immobilized lipase was evaluated by Bouwer and co-workers [113]. These authors suggested that the larger thickness of the reaction layer in hydrophilic membranes, as compared to hydrophobic membranes, allowed the retention of the full enzyme activity. A lipase adsorbed onto polypropylene membranes in a hollow-fiber system was used for the selective hydrolysis of menhaden oil [112]. The experimental set-up led to the release of about 88% of the fatty acid residues and retention of more than 90% of the aimed eicosapen-taenoic and docosahexaenoic acids in a space-time of 3.5 h, while the half-life of the enzyme, under ideal operational conditions was 170 h. The enzymatic synthesis of an aspartame precursor in an organic-aqueous membrane-assisted two-liquid phase system has been continuously studied by Isono and co-workers [121, 149,156,201]. Productivity was increased from 6.6 to 8.4kgm d [121]. 

Poly(acrylic acid) (PAA) was grafted onto the ultra-fine cellulose fiber surfaces via ceric ion initiation (Scheme 5). The carboxylic acid concentration could be controlled by varying monomer AA and/or ceric ion concentrations, and was determined by NaOH-HCl titration using phenophthlein as the indicator. Unless otherwise indicated, fibers with 3.6 mmol of COOH per g cellulose (lAA]/[Ce(IV)]-30) were used for enzyme adsorption and assay. The PAA activated cellulose fibers were immersed in 1.0 mg/ml lipase solution (pH 7.0) at room temperature for 24 hrs. The lipase adsorbed cellulose fibers were rinsed by pH 7 buffer and deionized water to remove loose lipase, then dried under vacuum at room temperature for 12 hrs. 

Ultrafine cellulose nanofiber Chen and Hsieh (2004) surfaces grafted with polyacrylic acid (PAA) and lipase adsorbed on to the fiber to obtain a functionalized mat. 

Also obtained by treatment of respropiophenone in a 9 1 (vol/vol) mixture of cyclohexane/tert-amyl alcohol with vinyl acetate (5 equiv) in the presence of Pseudomonas cepacia lipase adsorbed on Celite for 24 h at 40° (20%) [6761]. 

H- n-Butyl Rhizomucor miehei lipase adsorbed on an anion exchange resin (Novo Nordisk, Lipozyme IM)/(i"Pr)20 72 37 20 9.5 2.4 98... 

H n-Propyl Mucor Miehei lipase adsorbed on an anion exchange resin (Novozyme IM2D, Novo Nordisk + 30 mM water/supercritical CO2 28 50 P = 150 bar 15 62 4.7 105 ... 

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