Chemical Modifications of Protein and its Applications

1. Chemical Modifications of
Protein
Presented To: Dr. Rafiq Ahmed
Presented By: Zohaib Hussain
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2. Protein Engineering
Problem
Solving
Technique
Technology Research
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3. Chemical Modifications
Modification
Reactive
Side Chains
Oxidation Reduction Nucleophilic Electrophilic
Natural
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4. Deteriorations
Peptide bond scissions
Racemizations
β-eliminations
Formation of products
Reaction of proteins with added chemicals.
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5. Why chemical modifications?
• Modified intentionally
• Structure-function relationship
• Studies or for development of new products
• Improved products
• The techniques used in pharmacological, food and feed, or other
industrial areas
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6. Sulfhydryl and disulfide
• Catalytic sites of a wide variety of enzymes
• Maintenance
• Inactivation of SH enzymes by iodine
• Modify cysteinyl, tyrosinyl, tryptophanyl
resiudes
• Acidic pH, low temp, and excess of reagent
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7. Mechanism
• Human serum albumin and tobacco mosaic
virus
• Ovalbumin ,8-lactoglobulin, dihydrofolate
reductase, and papain
• Oxidation with iodine will led to the formation
of suIfenyl iodide derivatives.
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8. Recovery
Sulfenyl derivatives
sulfhydryl
• On addition of thiols
• Recovery of enzymatic activity,
• With the reduction, ranges from 50-100%.
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9. Reduction of Protein Disulfide
Bonds
WITH PARTIAL OR TOTAL RETENTION OF BIOLOGICALACTIVITY9

10. Application in Basic Protein
Chemistry
• Reactive and Active site modifications
• To alter physical and biological properties
• Radio-isotopic labeling
• Modifications for analytical proposes
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11. Applications For Food and
Nutritional Purposes
• Blocking of deteriorative reactions
• Physical properties
• Flavor and color
• Nutritional properties
• Aid the physical separation form crude
• Inactivate/remove undesirable substances
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12. Blocking of deteriorative
reactions
• Stages harvesting, processing, cooking, storage
• Brown color of bread crust
• Millard reaction (non-enzymatic browning)
• In-solubilize, colored, off-flavours
• Nutritive loss and possibility of toxicity
• Acetylation, methylation, isopropylation
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13. Texturization
• Protein rich products-Structure, Shape, texture
• Resemble those of conventional food products
• Meat Like materials from plant proteins-fillers
• Textured proteins- High pH, Substances-
Neutralization-desired physical property
• Recemization-serine
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14. Functional Properties
• Gelling ability, solubility, viscosity
• Contribution to nature of food product
• Baking industry-Proteins modified chemically
• Oxidants- Consistency and strength
• Enhance mechanical strength-disulfide
interchanges
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15. Application in Pharmaceuticals
• Interaction of proteins-Chemical reagents
• Drug act by direct inactivation of a target
molecule
• Covalent combination with the drug
• Naturally occurring toxins results in the body
• Chemical warfare
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16. Life time of drug
• Protein hormones
• Lower their rate of removal from the
bloodstream
• Efficiency/Frequency of admnistration
• Animal insulin by coupling to protamine-zinc
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17. Target Specific Transport
• To transport the substances to targets site
• Radioactive iodine or toxic substances attached to
antibodies in attempts to kill cancer cell
• Drugs-irreversible enzyme inhibitors
• Modifications for altering biological properties
• Glutaraldehyde's cross-linking effect on proteins is in
the preparation of prostheses for internal organs, e.g.
heart valves
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18. Every Ending is Just a Really New Beginning
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