Protein Structure Flashcards
What are properties of the peptide bond?
Very stable
Cleaved by proteolytic enzymes
Partial double bond
Flexibility around C atoms
What is the ‘backbone’?
A line following the peptide bonds
What is a ‘cartoon’?
A representation showing the fundamental secondary structures
What forces hold proteins together?
Van der Waals
Hydrogen bonds
Hydrophobic forces
Ionic bonds
Disulphide bonds
What are Van der Waals?
Weak attractive interactions between atoms due to fluctuating electrical charges.
What are hydrogen bonds?
Interaction between dipoles, involving a hydrogen and a oxygen/nitrogen
What are hydrophobic forces?
Uncharged and non-polar side chains
What are ionic bonds?
Occur between fully or partially charged groups
What are disulphide bonds?
Bonds between cysteine
What is the primary structure?
Linear sequence of amino acids linked by peptide bonds
What is the secondary structure?
Bonds forming between the primary structure, hydrogen bonds etc…
What is the alpha helix?
Hydrogen bonds between each carbonyl group
What is the beta sheet?
Hydrogen bonds between linear regions of polypeptide chains
Parallel or anti parallel sheets
What is the tertiary structure?
The overall 3D conformation of the protein?
What is the quaternary structure?
3D structure of a protein composed of multiple subunits
Same non-covalent interactions as tertiary structures
How to determine the structure of a protein?
Crystallography
X-ray diffraction
What are enzymes?
Biological catalysts, accelerate a reaction and provide a way to regulate the rate of reactions
What enzymes are used to indicate liver function?
Acid phosphatase
Alanine aminotransferase
What enzymes are used to indicate prostate cancer?
Alkaline phosphatase
What enzyme is used to indicate pancreas function?
Amylase
What enzyme is used to indicate renal function?
Angiotensin converting enzyme
What enzyme is used to indicate liver function?
Aspartate aminotransferase
What enzyme is used to detect muscle damage or myocardial infarction?
Creatinine kinase
What factors influence haemoglobin saturation?
Temperature
H+
P CO2
What is sickle cell anemia?
Genetic disorder characterised by the formation of hard, sticky, sickle shaped red blood cells
What is sickle cell caused by?
Single nucleotide mutation
From GAG to GTG
What is glutamic acid in haemoglobin substituted for?
Valine
At what condition is the haemoglobin in sickle cell affected?
Low oxygen concentration
With the eradication of malaria in some geographical areas, why does sickle cell trait persist in the population at such a high frequency?
It takes many generations to change gene frequencies
What is truncation?
Premature termination, stop code where it doesn’t belong
What is substitution?
Changing the amino acids
What is Conservative substitution?
Amino acid is changed with a similar amino acid, charged with charged, hydrophilic with hydrophilic etc…
What is Non-conservative substitution?
Mutation causes a completely different amino acid to be inserted
What are deletions?
When part of the protein is removed, or stops
What is misplacing?
When RNA is edited incorrectly, instead of removing an intron it carries on
What are immunoglobulins?
Antibodies, produced to bind to antigens typically toxins or proteins on the surface of microbial agents
What structure do antibodies have?
Beta sheets
How do antibodies bind to antigens with high affinity?
Close proximity of the antibody CDR regions and the antigen surface
Intimate contact allows the combination of relatively weak interactions to produce a strong binding surface
What is the portion of antigen bound known as?
Epitope
What forces are used for the antigen-antibody bind?
Van der Waals
Hydrogen bonds
What factors affect complementarity
Van der Waals
Hydrogen bonds
Charge
Bulk
Hydophobicity
