Substrates insoluble

Lakes are prepared by adsorption or precipitation of a soluble dye on an insoluble substrate (e.g., alumina). They are useful in fatty products that have insufficient moisture to dissolve dyes (coated tablets, cake mixes, hard candies, chewing gum). Lakes are insoluble in most solvents including water, have high opacity, are easily incorporated in dry media, and show higher stability to light and heat. They are effective colorants for candies, pills, fats, and oils. The main characteristics and differences between lakes and dyes are well documented. ... 

Hommel RK (1994) Formation and function of biosurfactants for degradation of water-insoluble substrates. In Biochemistry of Microbial Degradation (Ed C Rattledge), pp. 63-87. Kluwer Academic Publishers, Dordrecht, The Netherlands. 

The diastase activity was traditionally determined according to the Schade method in the earlier years (Schade et al., 1958). One unit of diastase activity (or more specifically, a-amylase), DN, is defined as that amoimt of enz)nne that converts 0.01 g of starch to the prescribed endpoint in 1 h at 37 °C under the experimental conditions. In this assay, a standard solution of starch, which reacts with iodine to produce a color solution, is used as a substrate for honey enzymes under the standard conditions (Rendleman, 2003). A recently developed procedure uses an insoluble, dyed starch substrate (Persano Oddo and Pulcini, 1999). As this substrate is hydrolyzed by ot-amylase, soluble dyed starch fragments are released into solution. After reaction termination and insoluble substrate removal by centrifugation, absorbance of the supernatant solution (at 620 nm) is measured. The absorbance is proportional to the diastase activity. This procedure has been widely adopted in the honey industry due to the convenience of a commercially available substrate and the simple assay format. 

FIG. 1 Reaction systems containing organic solvent, and corresponding theoretical concentration profiles for water insoluble substrate. solid biocatalyst organic phase aqueous phase or biocatalyst dissolved in aqueous phase. 

Mata, N.L., Moghrabi, W.N., Lee, J.S., Bui, T.V., Radu, R.A., Horwitz, I. and Travis, G.H. Rpe65 is a retinyl ester binding protein that presents insoluble substrate to the isomerase in retinal pigment epithelial cells. /. Biol. Chem. 279 635-643, 2004. 

Malmcrona-Friberg, K., Blainey, B. L. and Marshall, K. C. (1991). Chemotactic response of a marine bacterium to breakdown products of an insoluble substrate, FEMS Microb. Ecol., 85, 199-206. 

An almost infinite variety of chemical reactions is possible among soil, additives, and organic contaminate. However, at the moisture, temperature, and pressure conditions present at most sites, only a few reactions are responsible for most stabilization processes. Aside from such processes as absorption, volatilization, and biodegradation, chemical reactions include processes such as hydrolysis, oxidation, reduction, compound formation, and fixation on an insoluble substrate. 

Dry Weight of Final Product. The dry weight of the final product (containing mycelial biomass and unutilized insoluble substrates was determined by filtering 100 ml of sample through a pre-weighed filter... 

Water in oil microemulsions with reverse micelles provide an interesting alternative to normal organic solvents in enzyme catalysis with hydrophobic substrates. Reverse micelles are useful microreactors because they can host proteins like enzymes. Catalytic reactions with water insoluble substrates can occur at the large internal water-oil interface inside the microemulsion. The activity and stability of biomolecules can be controlled, mainly by the concentration of water in these media. With the exact knowledge of the phase behaviom" and the corresponding activity of enzymes the application of these media can lead to favomable effects compared to aqueous systems, like hyperactivity or increased stability of the enzymes. 

Epoxidation Oxone alone (1.5-2 equiv.) can effect epoxidation of alkenes. Yields are generally higher if the pH is maintained at 6 by addition of KOH. Water-soluble substrates (sorbic acid) are epoxidized in water aqueous methanol is used for water-insoluble substrates. 

The enantioselective esterification of 2-arylpropionic acids catalysed by a lipase was discussed earlier.26 Steady-state kinetics of the Pseudomonas cepacia lipase-catalysed hydrolysis of five analogous chiral and achiral esters (R)- and (.S )-(235 R1 = Me, R2 = H), (R)- and (reaction mixtures of water-insoluble substrates.212 The Km values were all die same and the apparent kcat values reflected the binding abilities of the alcoholate ions for the fast-reacting enantiomers. All the substrates are believed to be... 

Enzyme immobilization has been reported to improve the thermal stability of enzymes (1,2) and may also affect binding of substrates and inhibitors to the enzyme, thereby affecting the Michaelis constant and enzyme inhibition. Several previous studies have considered the advantages of immobilized enzymes with soluble substrates, and a few studies have also investigated the properties of immobilized enzymes with insoluble substrates. The main objective of the present work was to establish the effect of immobilization on the thermal stability of these enzymes, so that they may be used at elevated temperatures without significant activity loss. The immobilization conditions were varied, and their effect on the performance of the immobilized enzymes was analyzed with reference to their physiochemical and structural properties. 

Figure 5 illustrates the performance of immobilized cellulase in comparison with that of soluble cellulase. The small difference between the "crude" and "used" Spezyme CP profiles illustrates the very low uptake of soluble cellulase onto the support. Furthermore, soluble cellulase is much more active the dose of soluble enzyme is approx one-twentieth that of immobilized cellulase, once enzyme uptake is taken into account. Nonetheless, it is important to note that the immobilized enzyme is able to hydrolyze this insoluble substrate, albeit at a much lower rate. 

Recently, we adapted the Ortbo Clinical Diagnostics lipase slide test [29], a dry chemistry test system used in clinical biochemistry to measure the lipase activity in human serum for the determination of the lipase activity in pancreatic extracts. The substrate, l-oleyl-2,J diacetylglyceral, and the ancillary reagents are fixed in a multilayered film (Fig, 7). Upon addition of a lipase solution, die insoluble substrate becomes emulsified... 

The pancreatic enzyme it stored and secreted as a proenzyme with an additional seven residues at the N-tcmiinus, The proenzyme serves, like the other pancreatic proteinase zymogens, to prevent aotodigestion of the pancreatic cells. Upon secretion into the gastrointestinal tract, trypsin cleaves off these seven residues to produce the enzymatic form with full activity on insoluble substrates. On monomeric substrates, however, there is little difference between the catalytic activity of the proenzyme and of the activated enzyme [34],... 

Pancreatic carboxytester lipase, secreted by the pancreas as an active enzyme without proteolytic activation, displays broad substrate specificity and has therefore received many names in the literature carboxylesteraae, bile salt-stimulated (or activated or dependent) lipaae (due to its absolute requirement for bile salts to hydrolyze insoluble substrates), carbaxylester lipase or hydrolase, cholesterol... 

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