what are the basic A.A
when do protons dissociate
Acid-base titration is performed, and the amino acid is found to have 3 distinct pKg values: 2.2 for the carboxyl group and 9.2 and 10.7 for the ammonium groups. At
1) pH < 2.2
2) pH = 9.2 -10.7
3) pH > 10.7
What is the most likely net charge of the pictured amino acid?
* Very confused about the protonation and dissociation. PLEASE EXPLAIN STEP BY STEP. Really need to know this pat down for a huge exam tmr!! Thank you!!!!
Use the Henderson-hasselbach equation and solve for the ratio at each pH.
Basic amino acids are histidine, arganine, and lysine.
Isn't is if pH > pKa then it dissociates and if pH < pKa it protonates.
Based off that logic (which was used to explain the answer that I did not understand) how would you go about it?
NH3 protonated is +1
COOH dissociated is -1
etc etc
Thank you for your response, pls follow up!!
I understand that you are confused about protonation and dissociation of amino acids. I will explain the process step by step to help you understand it better. Let's break it down:
1. Protonation and dissociation: Protonation refers to the addition of a proton (H+) to a molecule, while dissociation is the process of breaking apart a molecule into its component parts. In the case of amino acids, protonation and dissociation occur due to the presence of ionizable groups, such as the carboxyl group (-COOH) and the amino group (-NH2).
2. Acid dissociation constant (pKa): The pKa is a measure of how easily an acid donates a proton. It provides information about the equilibrium between the protonated and deprotonated forms of an acid. For amino acids, we typically consider the pKa values of the carboxyl group and the amino group.
3. Net charge of an amino acid: The net charge of an amino acid depends on the pH of the solution and the pKa values of the ionizable groups. At a given pH, an amino acid can be either protonated (+) or deprotonated (-), and the net charge is the sum of these charges.
Now, let's consider your specific scenario:
1) pH < 2.2:
At this pH, which is less than the pKa of the carboxyl group (2.2), the carboxyl group will be protonated (+) while the amino group will not be affected. Therefore, the net charge would be +1 (+ from carboxyl group, 0 from amino group).
2) pH = 9.2 - 10.7:
At this pH range, which is between the pKa values of the ammonium groups (9.2 and 10.7), the carboxyl group will be deprotonated (-) while both ammonium groups will be protonated (+). Hence, the net charge would be +2 (+1 from each ammonium group, -1 from carboxyl group).
3) pH > 10.7:
At this pH, which is higher than the pKa of both ammonium groups, all the ionizable groups will be deprotonated (-). Consequently, the net charge would be -1 (-1 from each ammonium group, -1 from carboxyl group).
To summarize:
1) pH < 2.2: Net charge = +1
2) pH = 9.2 - 10.7: Net charge = +2
3) pH > 10.7: Net charge = -1
Remember to consider the pKa values, pH, and the protonation/deprotonation state of each ionizable group to determine the net charge of an amino acid at a specific pH.
I hope this explanation helps you understand the process of protonation, dissociation, and determining net charge of amino acids. Good luck with your exam!