Biochem

• What is the function of myoglobin?


  facilitate oxygen transport in respiring muscle tissue
• Myoglobin _ the effective solubility of oxygen in muscle tissue

  increases
• If iron becomes oxidized into ferric, it will form__ or __


  metmyoglobin (MetMb) or methemoglobin (MetHb)
• Do those two met forms bind oxygen?

  No, thei imstead bind the heme coordinates to a water molecule
• ___ converts the ferric iron center back to Feii

  methemoglobin
• What happens when oxygen binds to ferrous heme?

  it becomes the sixth ligand
• Does the oxidation state of iron change upon oxygen binding?

  No
• Does oxygen bind in the same spot as histidine?

  No, binds to opposite face
• What changes occur in the electronic state of heme upon oxygenation?

  blood color will change but iron remains in ferrous state
• Does the free heme in a solution have more affinity for carbon monoxide or oxygen?

  carbon monoxide
• What does the presence of His-E7 do?

  forces carbon monoxide to tilt away, reducing the affinity of myoglobin/hemoglobin for carbon monoxide
• Why should myoglobin and hemoglobin have reduced affinity?

  allows trace amounts of carbon monoxide to be generated during metabolism, so it will not occupy myo and hemo sites
• Hemoglobin


  tetrameric oxygen that transports protein in red blood cells
• Hemoglobin structure vs myoglobin


  hemoglobin has a shorter amino acid residue chain
• What happens to the heme iron when a molecule of oxygen binds to a heme in hemoglobin (Hb)?

  heme iron is drawn into the ring
• The __ histidine forms a hydrogen bond with water in response to oxygen binding

  distal
• The __ histidine moves towards the heme group in response to oxygen binding

  proximal
• His-93 is the__ histidine

  proximal
• His-58 or 63 is the _ histidine

  distal
• Structural changes of the heme upon oxygen binding


  iron atom in heme moves so that it becomes planar with the rest of the group, which will then pull histidine= more structural change
• What does the Bicarbonate buffer system regulate?

  plasma pH
• Where do the first 2 equilibria occur?

  in the blood of capillaries
• Where does the last equilibria occur?

  in alveoli of lungs
• carbonic anhydrase

  catalyzes the conversion of carbon dioxide to carbonic acid and back again
• T state vs R state

  T state has low oxygen affinity and R state has a high oxygen affinity
• Which way will the graph move in response to changes with R and T state?

  R: Left, T:right
• Bohr effect

  describes hemoglobins lower oxygen affinity secondary to increases in the partial pressure of carbon dioxide and/or decreased blood pH
• __ binds to hemoglobin and promotes oxygen release

  BPG
• What does BPG do in response to a gr

  shifts graph to the right= promoting oxygen delivery
• BPG and oxygen


  inverse relationship
• structural difference between fetal Hb and adult Hb

  fetal has two gamma chains instead of two beta chains
• fetal Hb vs BPG


  the gamma chains lack the histidine residues= weaker electrostatic interaction
• Does fetal or adult Hb have a higher oxygen affinity?

  Fetal Hb. weak interaction= greater oxygen affinity
• __ is caused by a mutation of the 6th amino acid of the beta subunit from a glutamate to a valine

  sickle cell anemia
• What is catalytic power?


  The ratio of the catalyzed rate to that of the uncatalyzed rate
• What are cofactors?


  nonprotein chemical compound needed for biological activity
• What are coenzymes? 


  organic molecules that serve as intermediate carriers of functional groups used in converting a substrate into product
• What are prosthetic groups? 


  tightly bound or covalently bound coenzymes
• What is a holoenzyme?

  the catalytic active enzyme with its cofactor bound
• What is an apoenzyme?


  the proteins with the prosthetic group removed