proteins Flashcards

1
Q

adult haemoglobin

A

contains two alpha and two beta subunits

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2
Q

foetal haemoglobin

A

contains two alpha and two gamma subunits

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3
Q

cooperative binding of oxygen in haemoglobin

A

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.

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4
Q

glycosylation as a PTM

A
  • 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
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5
Q

ABO blood groups

A
  • 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
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6
Q

hydroxylation of proline and lysine

A

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

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7
Q

sickle-cell anaemia

A
  • 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.
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