Selectivity and Specificity,Pseudomonas Cepacia,Chemoselectivity,Regioselectivity,vs Amino,S Monoester,Chymotrypsin,Dimethoxy Benzyl,Di Isopropyl

	Home
Protein and Enzymes Engineering Protein and Enzymes Engineering - Introduction Engineering of Macromolecules Basic Outline Protein Engineering vs Enzyme Engineering for a Biocatalyst Protein Engineering Rationale of Protein Enzyme Engineering Basic Assumptions for Protein Engineering Key Biocatalyst Properties that are Altered Through Protein Engineering Some Examples of Improved Kinetic Parameters of Enzymes Turnover Determined by k_cat Selectivity and Specificity Some Technologies Available for Enchancing Biocatalyst Characteristics Molecular Stability Catalytic Diversity Acquiring Knowledge for Protein Engineering Study of Protein Structure Three Dimensional Protein Modeling Perturbation Theory

Home >> Industrial and Microbial Biotechnology >> Protein and Enzymes Engineering >>Selectivity and Specificity

Your Ad Here	Selectivity and Specificity Specificity of many enzymes is often narrow, but for industrial use, sometimes a broad substrate specificity may be needed as in case of proteolytic and lipolytic enzymes in laundry detergents. In contrast, for production of most pharmaceuticals and chemicals, strict substrate specificity is needed. Stereoselectivity (selectivity on the basis of three dimensional structure) has also been an important area of research in recent years, particularly for synthetic biotransformations and chiral resolutions. Many highly stereoselective biocatalysts are already in large-scale industrial.
Enzyme specificity with respect to substrate (enantiomeric, prochiral, regio-and chemoselectivity) has also been altered in many cases by switching from aqueous medium to organic solvent. Some examples include the following: (i) In case of α-chymotrypsin, in water the activity of enzyme with hydrophobic substrate N-acetyl-L-phenylalanine ethyl ester (N-AC-L-Phe-OET) is 50,000 fold more than with hydrophilic N-acetyl-L-serine ethyl ester (N-AC-L-Ser-OET), but in octane the enzyme is three times less active with the former than with the latter. (ii) In case of subtilisin, in dichloromethane, the enzyme with the substracte N-AC-L-Phe-OET is 8 times more reactive than with N-AC-L-Ser-OET, while in t-butylamine the situation is reverse.
Stereoselectivity (prochiral or enantiomeric) is another important attribute of an enzyme that depends on the medium (aqueous or organic) and has been exploited for the industry. Following are some examples: (i) enantioselectivity of enzyme α-chymotrypsin, while using propanol as a substrate for transesterification of a medically important compound, methyl 3-hydroxy- 2-phenylpropionate, increases 20-fold on changing the solvent.	Your Ad Here
The enzyme prefers S-enantiomer of the substrate in one solvent and prefers R-enantiomer in the other. (ii) in α-chymotrypsin catalysed acetylation of 2- (3,5-dimethoxy benzyl)-1,3-propanediol, the dominant product is S-monoester in di-isopropyl ether or cyclohexane and R-enantiomer is found preferentially in acetonitrile or methyl acetate. Regioselectivity and chemoselectivity are also controlled by the solvent. Regioselectivity refers to preference of an enzyme for one out of several identical functional groups in the substrate molecule. For instance, preference for one of the two ester groups in an aromatic molecule or for one of several hydroxyl groups in a sugar is exercised by lipase from Pseudomonas cepacia. Chemoselectivity, on the other hand, refers to the extent to which an enzyme favours one of several functional groups (e.g. hydroxyl group vs amino group for acylation); this also depends strongly on the solvent.

	Home
Methods for Protein Engineering Site Directed Mutagenesis in Vivo Gene Modification Through Oligonucleotide Synthesis Breeding a Better Catalyst Using Random Events Artificial Random Mutagenesis Random DNA Shuffing Using Recombination Combination of Structure Based and Envolutionary Approaches Multienzyme Systems bi and Polyfunctional Enzymes by Gene Fusion Chemical Modification of Enzymes Production of Site Specific Nucleases Production of Artifical Semi Synthetic Oxido Reductases Flavo Enzyme Hybrid Enzymes Combinatorial Chemistry Organic Synthesis Libraries De Novo Design of Catalysts Some Early Achievements of Protein Engineering Possible Candidates for Future Protein Engineering Improving Enzymes by Using Organic Solvents