Micellar enzymology

Martinek, K. et al., Micellar enzymology its relation to membranology, Biochim. Biophys. Acta, 981, 161-172, 1989. 

The most striking effects in micellar enzymology are seen in dependencies of enzyme catalytic activity, k at, on surfactant degree of hydration. These dependencies are normally bell shaped (see examples in Fig. 5) the higher the molecular weight of the enzyme the... 

Micellar enzymology which employs microheterogeneous surfactant-organic solvent-water systems as reaction media prove to be exceptionally technological and prospective in application. Therefore, it seems necessary once more to draw attention to the properties of reverse micelles. 

Reversed micellar enzymology has been extensively studied [114-116]. However, neither a large-scale operation, nor the enzyme and product recoveries for its practical application have been successfully carried out. The reversed micelle is a favorable reaction field for... 

Since the appearance of micellar enzymology as a new field of research interest, proteases, being hydrophilic and relatively small, have been considered as good model systems for the effectuation of both hydrolytic and synthetic reactions in w/o microemulsions [44,55] (Table 13.2). These enzymes can be easily dissolved in the aqueous domains of w/o microemulsions and maintain their catalytically active conformation since they remain protected from the denaturating effect of both organic solvent and synthetic emulsifiers. In addition, the coexistence of aqueous, organic, and amphiphilic domains, which characterize w/o microemulsions, enables the contact of the enzymes with substrates of different polarities. 

Proteases, when solubilized in the aqueous core of reverse micelles, can catalyze the hydrolysis of various small model peptides. In most of the cases, the substrates are partitioned between the micelles and the external solvent while the hydrolytic reaction is taking place within the dispersed aqueous domains. Since the beginning of micellar enzymology, a-chymotrypsin and trypsin have been extensively studied in different reverse micellar systems, employing various model peptides as substrates. In almost all cases the reactions followed Michaelis-Menten kinetics. 

Reversed micellar enzymology has been studied by many researchers [1, 2]. The conversion of apolar compounds by enzymes entrapped in aqueous cores of reversed micelles has drawn the most attention. Reversed micellar enzymology requires not only a large-scale operation, but also enzyme and product recoveries for its practical application. There is still a lack of understanding of many aspects of enzyme behavior in reversed micelles. 

As mentioned above, the catalytic activity of an enzyme is determined by its conformation in reverse micelles, so the characterization of the enzyme conformation is an important aspect of the soInfrared spectroscopy is a powerful technique for structural characterization [76-78]. For a protein hosted in reverse micelles, the spectral features of the protein are always interfered by the IR absorption bands of the medium in addition to the congestion in their IR spectra. Fortunately, there is a transparent window in the 2500-2200 cm region. Incorporation of a vibrational probe with IR absorption frequencies in this region into proteins represents a promising strategy for the study of the conformation of a protein in a reverse micelle. Huang et ul. [79] incorporated a 4-cyanobenzyl... 

From the perspective of apphcations, the traditional micellar enzymology has found potential apphcations in the biosynthesis and bioresolution of chiral drugs and in the preparation of biodiesel (via transesterification reaction). Microemulsion-based gelation creates favorable conditions for the reuse of enzymes. As a solvent, room-temperature ILs have potential advantages over molecular organic solvents, so the use of I L-based microemulsions will bring new opportunities for and give fresh impetus to biocatalysis and biotransformation. 

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