Protein 2 Flashcards
Oligomerisation state
Number of polypeptide chains in a protein
Oligomer Protein
Protein containing multiple poly-peptide chains
Homo-oligomer
Protein consisting of identical polypeptide chains
Hetero-Oligomer
Protein containing non identical polypeptides
Protomers and an example
Identical subunits of a complex;
Haemoglobin contains α2β2- Dimer of αβ protomer
Transient protein interaction
Proteins that have temporary interactions
e.g. proteins that assist RNA polymerase II in beginning its job in transcribing DNA and creating mRNA
Permanent protein interactions example
Light and heavy chains of antibodies due to disulphide bridges
Non-obligate interactions example
Antibodies with pathogenic antigens
Obligate interactions
Protein interactions where one or both members must participate in to survive
3 Advantages of oligomeric proteins
Easier Expansion
Easy Repair
Alternate site of assembly in terms of production
Allows for specialisation of different domains
Homo-oligomer enzymes have increased catalytic rate
Ease of regulation of enzymes
Alpha Keratin (wool and hair) Sec, Tert, Quat structures
2 - Alpha Helix
3 - Twisting of Alpha Helix
4 - Coiled coil
Describe the distribution of secondary structure within fibrous proteins
They generally have one type of secondary structure
Foetal haemoglobin vs Adult haemoglobin
Foetal has a greater affinity for oxygen so the body of the mother does not ‘steal’ away the oxygen
Two states of Haemoglobin (Not as in Alpha and Beta)
T (Taught) - Deoxyhaemoglobin
R (Relaxed) - Oxyhaemoglobin
If you need help remembering, just think that oxygen’s binding relaxes the protein
Advantage of having 4 haemoglobin subunits
When oxygen binds to one subunit, the other subunits have conformational changes to turn them into the R state and give them greater O2 affinity
