Protein 2 Flashcards

1
Q

Explain the Hb subunit contacts ?

A

There is alpha 1 & alpha 2 and beta 1 & beta 2. There are more interactions between cyan and coral (alpha 2 and beta 2) than cyan and blue (alpha 2 and beta 1)

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2
Q

Does alpha1/beta2 interface change ?

A

Changes occur at alpha1/beta2 interface

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3
Q

Does alpha1/beta1 interface change ?

A

Alpha1/beta1 unchanged

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4
Q

The energy in the formation of the Fe-O2 bond formation drives ?

A

The T to R transition

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5
Q

Haemoglobins O2 -binding Cooperativity derives from?

A

The T to R Conformational shift

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6
Q

The Fe of any subunit cannot move into its haem plane without ?

A

The reorientation of its proximal His so as to prevent this residue from bumping into the porphyrin ring

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7
Q

The proximal His is so tightly packed by its surrounding groups that it can not ?

A

Reorient unless this movement is accompanied by the previously described translation of the F helix across the haem plane

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8
Q

Small change in pH of environment leads to ?

A

Large change in binding affinity

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9
Q

Higher pH i.e. lower [H+] promotes ?

A

Tighter binding of oxygen to haemoglobin

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10
Q

Lower pH i.e. higher [H+] permits ?

A

The easier release of oxygen from haemoglobin

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11
Q

In capillaries (low pO2), the H+ is taken up by ?

A

Hb- releases O2 and also drives forward reaction

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12
Q

In lungs (high pO2),O2 binding leads to ?

A

H+ released from Hb and drives reverse reaction and release of CO2

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13
Q

Bicarbonate is 100 x more soluble than ?

A

CO2. Otherwise CO2 would form bubbles in blood!

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14
Q

Deoxyhaemoglobin binds CO2 as ?

A

Carbamate

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15
Q

What does high [CO2] in capillaries ?

A

Stimulates Hb to release O2

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16
Q

What also affects Hb affinity for O2 ?

A

[Cl-]

17
Q

T-> R state involves breaking of ?

A

Salt bridges driven by Fe2 –O2 bond formation

18
Q

BPG binds to ?

A

Central cavity of deoxy Hb on its 2 fold between two b chains

19
Q

When is there no room for BPG ?

A

In R state

20
Q

The transition from deoxyhemoglobin (T state) to oxyhemoglobin (R state) occurs ?

A

Upon oxygen binding

21
Q

Explain Heterozygous individuals and Homozygous individuals with Sickle Cell Anaemia (SCA) ?

A

Heterozygous individuals – carriers

Homozygous individuals – diseased

22
Q

SCA results from ?

A

Defective Haemoglobin

  • Haemoglobins stick together
  • Red blood cells damaged
23
Q

What will this therefore lead to ?

A

Complications from low oxygen supply to tissues;

- Pain, organ damage, strokes, increased infections, etc.

24
Q

Incidences are highest among ?

A

Among Africans and Indians.

- Heterozygotes protected from Malaria

25
Q

Hydrophobic Val replaces?

A

Hydrophobic Glu on β chain