Hemoglobin 9/26 Flashcards
Myoglobin vs hemoglobin protein structures
Not similar at primary AA level.
Similar secondary
Similar tertiary
Myoglobin oxygen binding curve
Hyperbolic curve
NOT sensitive to small changes in O2 conc.
Storage until O2 needed by muscles
Hemoglobin oxygen binding curve
Sigmoidal curve
Cooperative binding
Transport of O2
Salt bridges in T-state Hgb
Lys+ (a1) to COO- (B2)
Arg+ and Asp- (a1) to corresponding AAs on a2
COO- to NH3+ (a1-a2)
What will decrease Hgb affinity for O2?
Acidosis: ⬆️H+ ⬇️ ph
⬆️CO2
⬆️temp
⬆️BPG
What is the Bohr effect?
CO2 generated in peripheral tissues + H2O forms carbonic acid, which dissociates into protons and bicarbonate. Deoxyhemoglobin binds to protons bringing them to lungs. In lungs, O2 binds to Hgb; Hgb releases protons that combine w bicarbonate to form carbonic acid. Carbonic anhydrase dehydrates it to CO2 which is exhaled.
Effects on altitude and BPG on Hbg
Normal - 38% oxygen released to tissues
High altitude - 30% of oxygen released to tissues
High altitude + BPG - 37% oxygen released to tissues
Hgb in diabetes
A1c - a2, (B-N-glucose)2
Hgb in B thalassemia
F - a2, gamma 2
Hgb in a-thalassemia
H - B4
Bart’s - gamma4
Which chromosomes are Hgb genes located on?
Chromosome 16- a1, a2
Chromosome 11- all non alpha Hgb
Production of globin synthesis during development
Constant high a
High neonatal gamma, low postnatal gamma
Low neonatal B, high postnatal B
Describe oxygen affinity in hbF (b-thalassemia) va HbA
In HbF gamma chains, serine replaces the histidine that reacts w BPG, causes a lower affinity for BPG, and a higher affinity for oxygen.
What is the globin mutation in sickle cell anemia? HbS
B globin mutation - glutamine replaced with valine. Hemolytic and vasoocclusive. Patch on deoxyHbS B subunits adheres to B subunits on normal Hb molecules.
