Hemoglobin, Bohr Effect, and Fetal Hemoglobin
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- čas přidán 7. 10. 2013
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In this video, I discuss Hemoglobin, the Bohr Effect, and Fetal Hemoglobin, as it relates to adult hemoglobin.
Hemoglobin has three allosteric inhibitors: H+ ion, carbon dioxide (CO2), and 2,3-Bisphosphoglyerate (2,3-BPG). All of them decrease hemoglobin’s affinity for oxygen by stabilizing the T (tight or taut) state of hemoglobin, which has a lower affinity for oxygen than the R (relaxed) state. When hemoglobin is in its R state, it has a high affinity for oxygen and binds oxygen tightly. When hemoglobin is in its T state, it has a low affinity for oxygen and releases oxygen.
In the lungs, the pH is relatively high (low [H+]), the amount of carbon dioxide is relatively low, and the amount of 2,3-BPG is relatively low. There are less of the allosteric inhibitors in the lungs. Thus, in the lungs, hemoglobin is in its R state, and it binds oxygen.
In actively metabolizing tissues, the pH is relatively low (high [H+]), the amount of carbon dioxide is relatively high, and the amount of 2,3-BPG is relatively high. There are more of the allosteric inhibitors at the actively metabolizing tissues. Thus, at the actively metabolizing tissues, hemoglobin is in its T state, and it releases oxygen. It’s worth mentioning that it’s not “bad” for hemoglobin to be in the T state. It’s actually necessary so that hemoglobin releases the oxygen to the tissues that need it. This is important to the function of hemoglobin: transporting oxygen from the lungs to the tissues.
The key difference between the structure of fetal hemoglobin and adult hemoglobin is that fetal hemoglobin has a serine residue substituted in for what is a histidine residue in hemoglobin. This particular amino acid residue is what interacts with the inhibitor 2,3-BPG. Histidine, being positively charged, is very attracted to the negatively charged inhibitor, 2,3-BPG. Serine, however, having a partial positive charge on the hydroxyl hydrogen in its side chain, is only partially attracted to the negatively charged inhibitor, 2,3-BPG. Thus, because of this, adult hemoglobin is more inhibited that fetal hemoglobin in its attraction for oxygen, and fetal hemoglobin has a higher affinity for oxygen that adult hemoglobin. This makes intuitive sense because a fetus receives oxygen from its mother’s blood; the fetal hemoglobin must be able to take oxygen molecules away from the mother’s adult hemoglobin in order to be supplied with oxygen itself.
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It's a video from 2013 but I just found it and want to thank you. This really helped me understand how the reactions work between Hb, O2, CO2 and H+. And also how allosteric regulator works for Hemoglobin.
YOU'RE SERIOUSLY HEAVEN SENT. EVEN THE DESCRIPTION LAYS IT ALL OUT. T minus 2 hours til my exam and this helped so much. Thanks again!
Haha! THANK YOU! I'm glad you found the video helpful. I hope you do well on your exam! :]
Ah! Thank the world of CZcams for your videos! Clarified like everything I was confused about! Final exam in 1 hr! 🙌🏽
Your videos are concise, hit on the important points, and extremely clear. i am extremely happy to have found these videos.
Thank You for helping me finally understand Hemoglobin. You rock!
This is amazing! Made the concepts so much simpler than I learned in class. Thank you!
N Ahmed Sweet! Happy to have helped! You're welcome!
Thanks !! it makes things easier to understand !
Your videos are so helpful!! Thank you!!!
Thanks! This helped my understanding greatly.
Man idk what you did with your life but I hope you accomplished great things. You're and awesome tutor. I would pay you the money I give to my shitty class for some lectures like this. Thanks
Thank you for the kind words of praise and appreciation!
So helpful, helping me see the bigger picture. Thanks. :)
thank you, thank you, thank youuu. Lifesaver !
Got to say, thanks for these videos, it's helped me a lot for my biomedical course =D
I'm glad, dude. You're very welcome! :]
You're the best THANK YOU
Thank you for the amazingly clear explanations! :D
Yuling Tsui You're very welcome! :]
oh man. these videos are so accurate to what im learning in class, and then i see that you are also from UCR! yay go highlanders! :)
Best 😍. You really made it very easy...
You are such a legend, thanks!
Liam Dransfield Lol. Wow! Thank YOU for calling me a legend! Haha!
Thank you! Very helpful. Thank you for taking the time to make the videos.
Sarah Lawrence Sure thing! I'm glad you found them helpful.
U rock man and im a fan
thanks. great video
"baby blue"
I feel that I'm lucky when I found you!
awesome explanation :) thank you so much...
so helpful
thank u
amazing video thank you
OMG u totally saved me from my bichem midterm tomorrow
parmiiidaaa Lol. Sweet! I hope you did well!
Hi you referred to a video before this one. Which video on Hemoglobin is that? Talking about the cooperativity. Thank you so much!!! This was so helpful!
Tank you sooo much
You're welcome sooo much!
The Histidine since it's found the myoglobin being positively charged amino acid but why saying it's the T- State of Hemoglobin conformation being stabilized . Kindly make mention of the connection between these two globular proteins Sir .
Hey great video :), but can you explain 2,3 bpg relating to high altitude.
King James Details aside, people who've grown accustomed to living at high altitudes (where O2 concentration/pressure is lower, essentially) have higher 2,3-BPG levels. The higher 2,3-BPG levels causes the oxy-Hb to more readily give up is O2 to the tissues. This way, the tissues are not O2-deprived, despite the lower O2 levels at higher altitudes. This is the basis for altitude training. Distance athletes will often train at higher altitudes over long periods of time so as to get their bodies adjusted to the lower O2 concentrations/pressures. This way, their bodies basically get better at getting O2 delivered to their tissues, helping to increase their performance during races, particularly races at lower altitudes.
•2,3BPG lowers the affinity of Hb for oxygen (raises the P50 of Hb from ~12 torr in aqueous solution to ~26 torr in blood - i.e. respiring tissue) Can you explain the info in parentheses? Its on my professors slides, how does this change the P50?
3wJblind0114 Yeah. The p50 of Hemoglobin (Hb) is the partial pressure of oxygen necessary to make Hb 50% saturated. 2,3-BPG (being an inhibitor of Hb) raises the p50. That means, with an inhibitor, Hb requires more oxygen (26 torr) to be 50% saturated, whereas without an inhibitor, Hb only requires 12 torr of pressure due to oxygen to reach 50% saturation. I apologize if this response is two weeks too late, though. :/
p-crease lol.@6:08
Lol. I'm glad I wasn't the only one laughing at myself.
Bookmark 10:26
pls mention in the video that what ever u said all is written it took me week to write down what ever u said and then after a 1week what i saw was ..... pls mention it
But I thought histidine is neutral at the physiological pH, how can it be the reason that maternal hb is more susceptible to 2,3 bpg?
+verdeapplesify I think it's because 2,3-BPG binds in the tissues, which is at a much lower pH due to CO2 from the muscles. The CO2 from the muscles is turned to carbonic acid. The extra protons flying around bind to histidine, which gives the it a positive charge, allowing the 2,3-BPG to bind. At least that's how I understood it!
Don't use dark colors on dark background, hard to see
That lung and actively metabolizing tissues are really confusing. >.>
That was too many ads for this one video
Ya boy gotta get paid. Lol. I hope you found the video helpful, though! :]
lol lets use baby blue since we are talking about babies XD
i can't see the writing through a microscope
just do full screen brah.