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Beta sheets regions can form when alpha helices fold in upon themselves in order to reduce their molecular free energy state
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Globular protein with random, helix and b-sheet forms
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- Additional hydrogen bonding can take place any time a hydrogen and electronegative oxygen/nitrogen are in proximity
- Can form electrostatic bonds or can be solvated
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Additional hydrogen bonding can take place any time a hydrogen and electronegative oxygen or nitrogen are in proximity
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Net result of all the different kinds of bonds result in a protein macromolecule will try to find an equilibrium structure dictated by its environment and tends to be structurally locked into a specific conformation by a range of forces
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- Tetramer
- Four tertiary globular proteins associating
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- Lipoprotein
- Proteins complexed with lipids, generally triglycerides and phospholipids
- Abundant in nature and have good emulsifying properties
- Examples: Egg yolk, and some milk proteins
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- Glycoprotein
- Proteins complexed with carbohydrate
- Can range from simple sugars to heterosaccharides to polysaccharides
- The carbohydrate is generally attached to the OH group of serine or threonine by an O-glycosidic bond or the amide group of asparagine, by an N-glycosidic linkage
- Examples: Ovomucoid in eggs and soybean glycoproteins
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- Metalloprotein
- Complex proteins which are complexed with a metal ion which is generally loosely chelated
- Examples: Fe++ in myoglobin and hemoglobin where Fe++ is chelated by a porphyrin ring structure
- Numerous enzymes have metal ions as prosthetic groups
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- Unfolding of the protein as it is denatured
- Tertiary structure unfolds, secondary structure unravels
- Leaves the peptide bonds more accessible to proteolytic enzymes
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- Denaturation results in reduction in solubility
- Hydrophobic domains become exposed
- Exposed hydrophobic domains bind together
- They aggregate together
- Precipitate out of solution
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- TD = Temperature of denaturation
- Shows how with increasing temperature, degree of order is decreased
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Shows the effect of pH on protein denaturation
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- Urea
- Can hydrogen bond competitively with the peptide linkage induced hydrogen bonds and disrupt both tertiary and secondary structure hydrogen bonds
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Urea can hydrogen bond competitively with the peptide linkage induced hydrogen bonds and disrupt both tertiary and secondary structure hydrogen bonds
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Water hydrogen bonding is integral to, and helps stabilize the structure of proteins, especially around charged groups
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- Detergents have both hydrophilic and hydrophobic groups
- They are able to bridge the hydrophobic and hydrophilic regions of the protein and result in the opening of the internal structure of a protein
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- Bubble within a foam
- Air is trapped within a protein/water matrix (bubble)
- Each bubble has thin membrane (interface) which separates the two
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Foam can cause denaturation at the interface between the hydrophobic and hydrophilic groups
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The easy way to tenderize meat, by using papain, an enzyme to speed it up
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The hard way to tenderize meat, using this tool and physical force
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