Lecture 7: Protein Structure and Function Flashcards
Protein Structure
Structural (fibrous):
- Filaments
- _____ 3° & 4° structure
- High proportion of ______ amino acids
- Example?
Structural (fibrous):
- Filaments
- STABLE 3° & 4° structure
- High proportion of HYDROPHOBIC amino acids
- Example_: COLLAGEN_
Functional aka:(_______)
- 3° & 4° structure
- Multiple structural domains in polypeptide chain(s)
- Function often involves a _________ change
- Example?
Functional (GLOBULAR)
- 3° & 4° structure
- Multiple structural domains in polypeptide chain(s)
- Function often involves a conformational change in shape
- Ie. HEMOGLOBIN
_______\_ is an important constituent of connective tissue
(4 Examples)
Collagen is an important constituent of connective tissue:
- tendons
- cartilage
- bones
- the cornea of the eye
Each collagen chain is a long Gly and Pro-rich _____-_handed helix
_____\_collagen chains intertwine into a _______\_ super-helical helix
Each collagen chain is a long Gly- and Pro-rich left-handed helix
Three collagen chains intertwine into a righthanded super-helical helix
4-Hydroxyproline in Collagen
Forces the ______\_ ring into a favorable pucker
Offers more _______\_ bonds between the three strands of collagen
The post-translational processing is catalyzed by __________\_
4-Hydroxyproline in Collagen
Forces the proline ring into a favorable pucker
Offer more hydrogen bonds between the three strands of collagen
The post-translational processing is catalyzed by prolyl hydroxylase
4-Hydroxyproline requires α-ketoglutarate, molecular oxygen, and ___________\_
4-Hydroxyproline requires α-ketoglutarate, molecular oxygen, and ascorbate (vitamin C)
The Incorrect Folding (Assembly) of a Protein is a Potential Source of _______ Proteins
The Incorrect Folding (Assembly) of a Protein is a Potential Source of Aberrant Proteins
Loss of protein structural integrity with accompanying loss of activity is called ______\_
Loss of protein structural integrity with accompanying loss of activity is called denaturation
Proteins can be denatured by:
- \_______
- _______
- _____\_ solvents
- ______\_ agents: i.e. urea and guanidinium hydrochloride
Proteins can be denatured by:
- heat or cold
- pH extremes
- organic solvents
- chaotropic agents: i.e. urea and guanidinium hydrochloride
Ribonuclease Refolding Experiment:
Urea in the presence of 2-mercaptoethanol fully ______\_ ribonuclease
When urea and 2-mercaptoethanol are removed, the protein spontaneously refolds, and the _______\_ are reformed
_______ alone determines the native conformation
Significance?
Urea in the presence of 2-mercaptoethanol fully denatures ribonuclease
When urea and 2-mercaptoethanol are removed, the protein spontaneously refolds, and the disulfide bonds are reformed
Sequence alone determines the native conformation
Proved that Tertiary Structure is determined by amino acid sequence
HSPs, Chaperonins, Protein Disulphide Isomerase, Peptidyl prolyl cis-trans Isomerase are examples of?
Chaperones
A soluble protein secreted in a misfolded state which deposits as an ‘amyloid’ (beta-sheet structure)
Amyloidoses
Alzheimer’s, Parkinson’s, Huntington’s are examples of _________\_
Alzheimer’s, Parkinson’s, Huntington’s are examples of localized amyloidosis
Post Translational Modifications(PTMs) can:
– direct protein to ________
– influence activity
– influence interaction with other ____\_or ____\_
– control _____\_ of the protein
Post Translational Modifications(PTMs) can:
– direct protein to a specific location
– influence activity
– influence interaction with other proteins or membranes
– control stability of the protein
Protein Modifications
- Disulphide bridge formation
– Catalysed by __________\_
• Partial proteolysis
–Example?
• Modification of amino acids (Permanent or Reversible)
Protein Modifications
- Disulphide bridge formation
– Catalysed by disulfide isomerase
• Partial proteolysis
–Insulin
• Modification of amino acids
– Either Permanent or Reversible
