Acidity and basicity in amino acids

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Discussion Overview

The discussion revolves around the acidity and basicity of amino acids, particularly focusing on the definitions and roles of different functional groups within amino acids. Participants explore concepts related to conjugate acids and bases, as well as the behavior of amino acids in aqueous environments.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion regarding the identification of acidic and basic groups in amino acids, suggesting that the acidic group is the NH3+ and the basic group is COO-, rather than the commonly understood -COOH and NH2.
  • Another participant references the concept of conjugate acids and bases, implying that understanding these terms may clarify the initial confusion.
  • A third participant suggests that the proper term for 'basicity' is 'alkalinity', which may indicate a differing perspective on terminology.
  • A later reply reiterates the initial confusion about acidity and basicity, emphasizing that individual amino acids exist as zwitterions in water, where the acidic part is associated with protons and the basic part is capable of accepting protons, hinting at the complexity introduced by side groups.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the definitions of acidity and basicity in amino acids, with multiple interpretations and terminologies presented, indicating ongoing debate and uncertainty.

Contextual Notes

There are unresolved assumptions regarding the definitions of acidity and basicity, as well as the roles of specific functional groups in amino acids. The discussion also touches on the behavior of amino acids in solution, which may depend on environmental conditions.

Rujano
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Hello! I'm having a hard time understanding the acidity and basicity of amino acids.

I read this: the acidic group in an amino acid is NOT the -COOH but the NH3+ and the basic group is COO- and not the NH2... why?

Thanks in advance!
 
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Just revise about "conjugate acids and bases" e.g.

http://chemwiki.ucdavis.edu/Physical_Chemistry/Acids_and_Bases/Conjugate_Acids-base_Pairs#Conjugate_Acid-Base_Pairs

"The conjugate acid of a base is formed when the base gains a proton" etc.
 
Last edited by a moderator:
The proper term for 'basicity' is 'alkalinity'.
 
Rujano said:
Hello! I'm having a hard time understanding the acidity and basicity of amino acids.

I read this: the acidic group in an amino acid is NOT the -COOH but the NH3+ and the basic group is COO- and not the NH2... why?

Thanks in advance!

Individual amino acids exist as zwitterions in plain water. Therefore, the acid part will be the group with the protons and the base will be the group capable of accepting a proton. You haven't asked about the side groups yet. That's where it gets interesting.
 

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