Molecular Stability,Encapsulation,Immobilization,Bacillus Stearoterrmophilus,Ribonuclease,Chymotrypsin

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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 >>Molecular Stability

Your Ad Here	Molecular Stability Stability of biocatalyst affects economics of a bioprocess and, therefore, is a major concern of the industry. The stability may be influenced by (i) temperature, (ii) ionic strength, (iii) pH, (iv) presence of denaturants among substrate/products, organic solvents, surfaces or interfaces. The molecular stability of enzyme is though an intrinsic property of the molecule (amino acid sequence and tertiary/quaternary structure of enzyme), there are methods available for enhancing enzyme stability (encapsulation, immobilization and cross-linking).
A study of extremophiles (organisms growing in extreme conditions) and their enzymes (with T_opt=80-130ºC; below 0°C) has greatly helped in understanding of the molecular mechanism responsible for stability. However, the enzymes from these extremophiles exhibit reduced catalytic rates, if used at normal temperatures (20oe to 50°C). But structural. stability can be improved in nature by introducing salt-bridging networks and can be artificially engineered by site-specific mutagenesis, enzyme evolution and gene shuffling.
For example, catalytic stability of xylose isomerase used in fructose syrup industry has been achieved by strain selection, immobilization and crosslinking, classical mutagenesis, or random mutagenesis. In contrast, 340 fold increase in stability of a protease (from Bacillus stearothermophilus) at 100ºC was achieved by eight site specific mutations. This was achieved without compromising catalytic activity, although generally it is believed that catalytic activity goes down with increase in stability.	Your Ad Here
Instability of enzymes can be irreversible and induced by high temperature, or it may be reversible and induced by heat. This is attributed, to water causing (i) conformational changes, (ii) deamidation of Asn/Gln residues and (iii) hydrolysis of peptide bonds. Instability of enzymes in water may also be attributed to proteolysis. However, enzymes are more thermostable and resistant to proteolysis in organic Solvents. For instance, porcine pancreatic lipase, ribonuclease and α-chymotrypsin at 100ºC have half life of several hours in anhydrous solvents, although in water they are inactivated at 100ºC within seconds. Similarly, Tm of bovine pancreatic ribonuclease is 124ºC in anhydrous alkane-nonane, while the Tm in water is only 61°C.

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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