basicity of amino acids

[ineedauniqueusername]

I was wondering why histidine < lysine < arginine are in this order of increasing basicity, if histidine has a more stable conjugate acid (protonated form) due to resonance?

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[DrRiker]

Arginine has a chai tea latte before bonding with the AA fam.

 

[ArteryStudyPainting]

Would it be because the resonance allows for a more stable acid with higher strength, thus less basicity [ and a lower strength in terms of basicity]?

 

[DrRiker]

Would it be because the resonance allows for a more stable acid with higher strength, thus less basicity [ and a lower strength in terms of basicity]?

A stronger base will have a more stable (weaker) conjugate acid, i.e. the conjugate acid will be happy keeping an additional proton in its squad. I think this is what you meant, but needed to clarify.

 

[ArteryStudyPainting]

A stronger base will have a more stable (weaker) conjugate acid, i.e. the conjugate acid will be happy keeping an additional proton in its squad. I think this is what you meant, but needed to clarify.

Right. In the most simplest of terms, I always learned it as a balance: Whatever is high, means it'll be low in the other based on those above tendencies you talked about.

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