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Biochem > Hemoglobin I & II > Flashcards

Hemoglobin I & II Flashcards

1
Q

Basic equipment of Hemoglobin’s binding site

A

beta-2 F8 contains proximal histidine
beta 2-E7 contains distal histidine
alpha1 C chain interfaces “elbow point” on alpha chain, causes conformational alteration in the other subunits to be optimally primed for oxygen uptake

process of oxygen uptake initially occurs in beta2, F helice

heme group containing iron

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2
Q

Bonding patterns in hemoglobin

A

beta 2 F8’s proximal histidine chelates Fe2+’s 5th coordination site, pulling it .4 angstroms from the plane

oxygen binds to Fe2+’s sixth coordination site

Oxygen forms superoxide stabilized by distil histidine donating a hydrogen bond to prevent free radical

Fe in 3+ state is called methahemoglobin, usless molecule

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3
Q

when when you find heme’s iron group in a +3 valence state, and what do we call this group?

A

oxidizing agents (toxins )

methemoglobin

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4
Q

Iron in heme and free iron

A

Iron is stabilized in the 2+ state in heme, and momentarily oxidized to 3+ during the binding of oxygen which pulls it BACK INTO THE PLANE of the porpheryn ring

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5
Q

3 blood plasma proteins, site functions and why

A

haptoglobin: grabs hemoglobin
hemopexin: grabs free heme in blood
transferin: grabs free iron

iron is toxic, catalytically producing free radicals in the blood.

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6
Q

hemoglobins fetal to adult

A

fetuses have alpha gamma (ay) hemoglobin subunits

by one year gamma has been “shut down” and betas have been activated.

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7
Q

Typically oxygen binds to ____ first

A

beta, F8 proximal histidine

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8
Q

Sicle Cell: why

A

amino acid substitution between a hydrophobic valine (interior) and a hydrophilic amino acid (glutamine)

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9
Q

Sicle cell: where

A

beta chain

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10
Q

Beta chain diseases are typically

A

worse than alpha chain diseases

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11
Q

Hb S

A

sicle cell anemia, Hb A wildtype

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12
Q

How does methemoglobin relinquish its oxygen?

A

methemoglobin reductase, which is an NADH: it contributes electrons to the iron and reduces it

the distal histidine also assists

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13
Q

Allosteric activity of hemoglobin

A

conformation change due to stimulation at a site other than oxygen binding site

can inhibit or stimulate oxygen

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14
Q

Hemoglobins conformation states

A

R state (oxygenated) and T (deoxygenated)

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15
Q

Homologous Proteins to Hemoglobin

A

myoglobin: takes oxygen FROM rbcs, does not supply them.

has a higher affinity for oxygen than RBCs

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16
Q

Allosterics: H and CO2

A

protons bind to hemoglobin —> T conformational state (BOHR EFFECT) Low pH

CO2 bind to hemoglobin —> T state

17
Q

pH of a muscle cell is

A

between 7.2-7.4, very acidic environment

18
Q

Haldane Effect

A

Oxygen drives off the CO2 and H in the lungs

19
Q

Glycolysis does what

A

produces H in the cells

20
Q

2,3-BPG

A

will be elevated in response to living in a higher altitude

negative allosteric effector: enhances offloading of oxygen

21
Q

H–Hb–CO2 is the result of the

A

bohr effect (rightward shift)

result of mass action

more O2 in tissues, more CO2 in RBCs

22
Q

O2-Hb is the result of the

A

Haldane effect, O2 diffuses into lungs and replaces CO2 and protons

23
Q

Evolutionary Time Line of Hemoglobin: from Leg-to Hemo

A

DIVERGED 800+ million years ago leghemoglobin/myoglobin/hemoglobin alpha/hemoglobin delta

DIVERGED 500+ million years ago
myoglobin, alpha and beta hemoglobins

DIVERGED 350+ million years ago
Hemoglobin alpha from hemoglobin beta

24
Q

Hemoglobin A has

A

alpha2beta2 adults

25
Q

Hemoglobin A2

A

alpha2delta2 adults, 2%

26
Q

Hemoglobin F

A

gamma chains (fetal)

27
Q

What is the mutation in the hemoglobin F that allows it to have a higher affinity for oxygen than hemoglobin A?

A

residue that binds 2,3 diphosphglycerate

28
Q

Heme

A

heterocyclic tetrapyrole structure (porphyrin ring) with an iron molecule in the middle

planar AND hydrophobic

bound to globin chain

29
Q

What kind of cooperativity does myoglobin have?

A

the OPPOSITE of cooperativity: it’s just ONE subunit, a different gene, and holds on to oxygen

30
Q

What molecules are in the RBC?

A

1) hemoglobin
2) molecules involved in pyruvate
3) methemoglobin reductase
4) enzyme responsible for converting intermediate in glycolysis from 1,3-DPG to 2,3-DPG

31
Q

Which way will the oxygen curve shift in the presence of 2,3-DPG

A

rightward, reduced affinity for oxygen

32
Q

RBCs need atp? if so, why?

A

work, keeping out sodium and calcium

Biochem (17 decks)

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