Enzymes physiochemical properties

In this article, we report the cloning in Escherichia coli and sequencing of an Orpinomyces P-glucosidase cDNA. The enzyme was overexpressed in and secreted from the yeast Saccharomyces cerevisiae. Physiochemical properties of the secreted enzyme were determined after it was purified. Its applicability for cellulose saccharification was also assessed. 

Molecular modeling techniques can be used to fit novel compounds into the binding site. They need not be structurally similar to the natural substrate but the dominant physiochemical properties should be similar. Modifications can be made to the molecule to improve the fit. This will increase specificity for the target enzyme. Substituents can be added or modified so that regions in the enzyme interact favorably with parts of the inhibitor. Electrostatic interactions, hydrophobicity, and hydrogen-bonding can be included in the fitting process. By judicious choice of substituents, both in vitro and in vivo activity can be optimized. Substituents could be added or modified to... 

In order to make a useful biosensor, enzyme has to be properly attached to the transducer with maintained enzyme activity. This process is known as enzyme immobilization. The choice of immobilization method depends on many factors such as the nature of the enzyme, the type of transducer used, the physiochemical properties of analyte, and the operating conditions [73]. The major requirement out of all these is its maximum activity in immobilized microenvironment. Enzyme-based electrodes provide a tool to combine selectivity of enzyme toward particular analyte and the analytical power of electrochemical devices. The amperometric transducers are highly compatible when enzymes such as urease, generating electro-oxidizable ions, are used [74]. The effective fabrication of enzyme biosensor based on how well the enzyme bounds to the transducer surface and remains there during use. The enzyme molecules dispersed in solutions will have a freedom of their movement randomly. Enzyme immobilization is a technique that prohibits this freedom of movement of enzyme molecules. There are four basic methods of immobilizing enzymes on support materials [75] and they are physical adsorption, entrapment, covalent bonding, and cross-linking, as shown in the Fig. 36. 

The reactivity of both endogenous compounds and xenobiotics with CYP is fairly broad, and is governed by a complex combination of physiochemical and structural properties [5]. A comprehensive review of this enzyme system and its critical role in the mechanisms of toxicity for many important chemicals is beyond the scope of this chapter, and the reader is directed to reviews on the topic [6-10]. 

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. 

Tortoise Trionyx gangeticus) lysozyme has been purified and the crystallized form was found to be homogeneous on polyacrylamide gel electrophoresis in sodium dodecyl sulphate, on immunological tests, and on sedimentation. The physiochemical and enzymic properties of the enzyme (average mol. wt. 1.54 X 10 by sedimentation and diffusion) were strikingly similar to those of the hen enzyme. The tortoise molecule underwent pH-dependent expansion at pH 2 and dimerization above pH 5.7. Further comparisons were made with hen and turtle lysozymes. 

The book looks deeper into lipases, which are hydrolytic enzymes that have great potential in many industrial applications. The main sources, structure, and features of lipases are presented, with an emphasis on their specificity and interfacial activity. Various industrial applications and property improvements are also discussed. The book focuses on lipase immobilization and its advantages over soluble lipases, where its effects on the physiochemical characteristics, namely, activity and stability, of lipases are discussed. Different immobilization techniques are described, and examples of various immobilization materials are given. In addition, different bioreactor configurations using immobilized lipases are described. 

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