proteins Flashcards
adult haemoglobin
contains two alpha and two beta subunits
foetal haemoglobin
contains two alpha and two gamma subunits
cooperative binding of oxygen in haemoglobin
haemoglobin must bind oxygen effeciently in the lungs, and release oxygen in the tissues. so, binding of one oxygen makes the affinity at other sites higher, release of an oxygen reduces the affinity at other sites. a sigmoidal curve is the signature of cooperativity.
glycosylation as a PTM
- attachmemt of a carb
- protects against digestion
- found particularly in extracellular and cell surface proteins
- sugars attached to asparagine (N), serine (S) and threonine (T) residues
- involved in cell-to-cell recognition
- aids in protein folding and can influence targeting of newly synthesised protein to its destination
ABO blood groups
- O-linked olgiosaccharides on RBC proteins and lipids.
- all antigens share the O carbohydrate foundation
- A and B have an extra monosaccharide:
A= N-acetylgalactosamene
B= galactose
hydroxylation of proline and lysine
collagen- polypeptide consists of several hundred repeats of Gly-Pro-Hydroxypro.
hydrolysed lysine residues are involved in collagen cross-linking
Vit C required for pro and lys hydroxylation- deficiency leads to scurvy
sickle-cell anaemia
- caused by a single change in the beta subunit of haemoglobin
- individuals with a single change are generally asymptomatic.
with 2 copies the haemoglobin aggregate, distorting erythrocytes. sickle cells obstruct capillaries causing intense pain and organ damage.