Globular Proteins

Question 1

CO binding to Hb

Answer 1

Heme binds with greater affinity to CO than O2, small amounts drastically reduce Hb’s ability to deliver oxygen to tissues

Also true of cyanide, SO, sulfide and H2S

Question 2

Bohr Effect

Answer 2

pH (H+) is an allosteric effector of Hb; when [CO2] is high / pH is low, histidine is protonated resulting in stabilization of T state and the release of O2 more readily

Question 3

2,3-BPG

Answer 3

Allosteric modifier of Hb that only fits in cavity of T HB; stabilizes T form of Hb which favors dissociation of O2.

2,3-BPG is higher in concentration in high altitudes, during airway obstruction, and in CHF

Question 4

Fetal Hb

Answer 4

Less positive sites in open cavity due to OH groups –> less binding of 2,3-BPG –> increased affinity for oxygen compared to maternal Hb