12-11-2012, 06:20 PM
PROTEN ENGINEERING
PROTEN ENGINEERING.pptx (Size: 264.95 KB / Downloads: 25)
Deliberate design and production of proteins with novel or altered structure and properties, that are not found in natural proteins.
Why Engineering Proteins ?
To study protein structure and function
Applications in industry (enzymes) and medicine (drugs)
-- New and improved proteins are always wanted.
Protein Functions
Structure
collagen : Structural support
Transport
Hemoglobin : transports oxygen from the lungs to cells
Storage
Myoglobin : stores oxygen in muscles
Hormones
Insulin : protein hormone controls blood glucose level
Enzymes
Alcohol dehydrogenase : that breaks down alcohols
Chemical modifications
One of the first way and a re-emerged method for altering protein properties.
Polyethylene glycol (PEG) modification of protein surface amino groups reduces immunoreactivity, prolongs clearance times, improve biostability, increase the solubility and activity of enzymes in organic solvents.
Proteins with new properties can be obtained by direct evolution
DNA in cells are randomly mutated: chemical mutagens (e.g., hydroxylamine, sodium bisulfate), enzymatic synthesis, mutagenic strains of bacteria (with deficient repairing systems).
Can be applied when the current theories are inadequate to predict which structural changes will give improvement on certain property.
Appropriate procedures for screening or selecting for desired properties are needed
Protein could be made to evolve in vitro
DNA shuffling: in vitro homologous recombination and in vitro protein evolution.
Random mutagenesis by error-prone PCR(with excess of one dNTP) to generate diversity of templates (naturally occurring homologous genes can also be used).
Selection under increasing selective pressures (antibiotics, pH, organic solvent).
Combination with High-throughput screening