Proteins Flashcards
Primary sequence?
Sequence of amino acids in a polypeptide
Secondary structure?
Spatial arrangement of R groups that are near each other in a sequence
What are the types of secondary structure?
- Alpha helices
- Beta sheets
- Turns
How are alpha helices stabilised?
H bonds between NH and CO groups in the next “spin” of the helix
What stabilises beta sheets?
H bonds between amide groups of sheets running parallel
Tertiary structure?
Interactions between R groups that are far away from each other in the sequence
What stabilises tertiary structure?
- Van der waals
- Ionic
- H bonds
- Disulphide bridges
- Hydrophobic interactions
What residue forms disulphide bridges?
Two cysteine residues
Where can disulphide bridges form?
- Intermolecularly
- Between two different polypeptides
Quaternary structures?
- Spatial arrangement of polypeptide chains in multi chain proteins
What structure remains in tact after denaturation?
Primary
What does denaturation effect?
- Reduces solubility
- Loses biological activity
- Easier to digest
What is glycosylation?
Post translational modification where a sugar is added via an amino acid
What is one example of a glycoprotein?
Immunoglobulins
Where does glycolysation occur in the cell?
- ER
- Golgi
Function of lipoproteins?
Transport through the blood
What do lipoproteins transport in the blood?
- Water
- Fat
- Cholesterol
What are metalloproteins?
- Protein with a bound metal ion
Function of metalloproteins?
- Enzymes
- Signalling
- Transport
What is co-operative binding using haemoglobin as an example
- O2 binds to one subunit
- Conformational change in other subunits increases their affinity for O2
What causes sickle cell anaemia?
HYDROPHILIC glutamic acid substituted by HYDROPHOBIC Valine
What is the structure of collagen?
Coiled polypeptides in a helix structure
What is scurvy caused by?
Vitamin C deficiency
What does a vitamin C deficiency cause?
Formation of weaker collagen
Effects of osteogenesis imperfecta?
- Collagen can’t form the tight coil
- Secondary and tertiary structure lost so brittle collagen produced
What happens if a mutation causes no LDL receptors to reach the cell membrane?
- No receptors
- LDL not released
What disease can result from the LDL receptor mutation?
Familial hypercholesterolemia
What does FH result in?
Early CVD
