Flashcards in Lecture 8-Seidler: Hemoglobin Deck (40)
Bind to distinct sites NOT ACTIVE SITE, induce conformational change to inhibit O2 binding
Exercise allows for 66% drop in O2 offloading, but 2,3-BPG w/ exercise allow for:
77% offloading...this makes for more efficient use of the O2...
If all three negative allosteric controls are present O2 can drop off to:
88%, Low pH, CO2 elevation and 2,3-BPG controls present
Training in the altitudes produces:
Mobilization of hemoglobin in lower affinity state
Resting state- oxyhemoglobin state- less constrained
Tense state; deoxyhemoglobin; "trying to push O2 out" ; constrained by subunit-subunit interactions.
Fetal Hb affinity to maternal:
Higher affinity to remove O2 from maternal Hb. This helps the fetus to obtain O2 from mom.
What's the deal w/ 2,3-BPG and fetal Hb?
Fetal Hb does produce 2,3_BPG, but this sequence is different and is unable to bind in the gamma of Hb F...it is just unable to interact...
Switch and lock Mechanism (sequential)
1-O2 binds in 6th position in the pocket of FE+2 and distal His (E7)
2-This pulls Fe+2 into plane of heme
3-Fe+2 movement pulls the proximal histidine (F8)
4-F8 pulls the F helix, and consequently G helix.
5-Sliding of F and G in one complex affects the E helix on other subunit [d/t now being in higher affinity state]