Thank you! 🙏 I can't believe how simply you explained this! I have been trying to figure out how to do this for like a week because my current pHd professor was super overcomplicating it, thank you thank you thank you!!!!
I think there is a mistake toward the last NH3+ group at pka 9.7. I think the charge should be -1 because the net charge right after pka 6 and before pka 9.7 is already 0. hence when have another depronotation after pka 9.7 it is supposed to have -1 over all here.
Why do we use COOH as the R group for Glu when in another example we used RH+ just as we used for His, Arg, and COO-? If we use RH+ for our R group instead of COOH, wouldn't that change our starting charge too?
Since you imagine that you are starting with the peptide at a low pH, everything will be protonated. Then the groups will deprotonate, starting with the lowest one. How you know they are neutral, positive, etc? You have to memorize the structures :) and then understand what the group looks like when it’s in the acid form vs the conjugate base form
you are right that they both have RH+ when the R group is protonated, but you have to look at the pKas to know which deprotonates first as you raise pH; they have different pKa values
hello um I don’t mean to be mean or something i just have a question? aren't we supposed to take the one before and after the 6 one? like it's 0 charge on ph 6 so we should take 4 and 9 right? i don't know i don't get it well pls respond i have an exam xD thanks in advance
this video has taught me more than my lecturer who has a PhD in biochemistry at an Ivy League University. Thank you so much.
Note: there’s a mistake on the overall charge of the peptide in the last step: it should be -1 not +1. Everything else is right :)
👍🏻
Thank you, for clarifying I couldn’t wrap my head around that.
Thank you! 🙏 I can't believe how simply you explained this! I have been trying to figure out how to do this for like a week because my current pHd professor was super overcomplicating it, thank you thank you thank you!!!!
This video just boosted my mark to above 80%. This work was never explained to us so thank you so much. Will definitely recommend your videos
I was so lost after my lecture. This cleared it up a lot! Very simple method, thank you :)
This is the best method I've seen so far!
Good method. Just got to remember as pH raises it exceeds pka of ionizable groups from lowest pka to higher pka in order.
I think there is a mistake toward the last NH3+ group at pka 9.7. I think the charge should be -1 because the net charge right after pka 6 and before pka 9.7 is already 0. hence when have another depronotation after pka 9.7 it is supposed to have -1 over all here.
Wow, as a student who has a lack of resources to study from this actually helped a lot, thanks this is much appreciated ❤
Very useful video with detailed explanation🥰👍
This is a great video. Preparing for the MCAT while also taking Biochem. Truly helpful. Thank you.
Why do we use COOH as the R group for Glu when in another example we used RH+ just as we used for His, Arg, and COO-? If we use RH+ for our R group instead of COOH, wouldn't that change our starting charge too?
You don't use RH+ for the COOH group bc COOH is neutral; protonation of a group does not always mean the group will be positive.
I'm pretty sure the charge at at the lowest pH should be +2(arg.+1 and n-terminal of Glu +1) Where did the 3 positive charge come from?
Thank you for your explanation. I'm having some difficults and this video really helped me!
best method I've seen! thanks for the super clear explanation!
I would like to ask, how will I know which R group can I protonate and when will it be positive or neutral? =)
Since you imagine that you are starting with the peptide at a low pH, everything will be protonated. Then the groups will deprotonate, starting with the lowest one. How you know they are neutral, positive, etc? You have to memorize the structures :) and then understand what the group looks like when it’s in the acid form vs the conjugate base form
@@DrMonaUCD thank you for your reply!
Excellent explanation
thank you for the clear explanation!
can you please find the pI for ala-arg-gly.
this was very helpful thank you!
Pka of carboxly group of glutamate is 2.19
This video was super helpful!
Echoe Malone thank you!
What about Arginine ? Why Glutamine ,the Ionizable group that has to deprotanate after histidine? Because histidine and arginine carry the same RH+
you are right that they both have RH+ when the R group is protonated, but you have to look at the pKas to know which deprotonates first as you raise pH; they have different pKa values
You are great! Thank you
From what book did you get this problem from?
Lehningeer
Careful of the mistake after pka 9.7
Doesn’t mess with the end result but it should have gone to -1 not +1
hello um I don’t mean to be mean or something i just have a question? aren't we supposed to take the one before and after the 6 one? like it's 0 charge on ph 6 so we should take 4 and 9 right? i don't know i don't get it well pls respond i have an exam xD thanks in advance
Oh no no sorry I mixed ph and pka’s my bad no need to bother
The video is good but you're so slow lol