Lesson 2.3. Protein Denaturation

Protein hydrolysis

• reverse reaction for peptide formation

• -COOH and -NH2 are regenerated for each amino acid in the peptide

Protein digestion

• enzyme-catalyzed hydrolysis of ingested protein

• resulting AAs are absorbed by the body for the synthesis of new proteins

re-synthesize needed molecules

Hydrolysis of cellular proteins is an “on-going” process to ____________________.

partial hydrolysis

protein chain is broken down to amino acid products and small peptides

complete hydrolysis

protein is broken down to individual amino acid residues

Protein Denaturation

partial or complete disorganization of a protein’s 3D shape as a result of disruption in its 2°, 3°, and 4° structural interactions

1° structure of the protein

Denaturation does not affect the a.______________________ but it results into the b.______________________ of the protein.

a = ?

loss of biochemical activity

Denaturation does not affect the a.______________________ but it results into the b.______________________ of the protein.

b = ?

Renaturation or refolding

process of reversing denaturation of proteins but not common to happen since denaturation is most often irreversible

Physical

Consequences of Protein Denaturation:

• It will exhibit decreased solubility and will eventually precipitate out of a solvent

Chemical

Consequences of Protein Denaturation:

• It will exhibit increased viscosity

Biological

Consequences of Protein Denaturation:

• It may result to loss of hormonal and/or enzymatic activity

Physical

Physical VS Chemical Denaturing Agents?

• Heat

Physical

Physical VS Chemical Denaturing Agents?

• High Pressure

Physical

Physical VS Chemical Denaturing Agents?

• UV Rays

Physical

Physical VS Chemical Denaturing Agents?

• Agitation/Shaking

Chemical

Physical VS Chemical Denaturing Agents?

• Acids/Bases

Chemical

Physical VS Chemical Denaturing Agents?

• Organic Solvent

Chemical

Physical VS Chemical Denaturing Agents?

• Salts of Heavy Metals

Heat, Microwave Radiation, and Ultraviolet Radiation

Denaturing Agent:

• disrupts H-bonds causing violent molecular vibration

Violent Whipping/Shaking

Denaturing Agent:

• cause globular shapes to elongate then entangle

Detergent

Denaturing Agent:

• affects R-group interactions

Organic Solvent

Denaturing Agent:

• interferes R-group interactions by forming H-bonds

Strong Acids and Bases

Denaturing Agent:

• disrupts H-bonds and salt bridges causing hydrolysis

Heavy Metal Salts (ex. Hg, Ag, Pb)

Denaturing Agent:

• combines with -SH groups producing poisonous salts

Reducing Agents

Denaturing Agent:

• reduces disulfide (-S-S-) bridges producing (-SH)