Re: [AMBER] Histidine tautomer state and pKa?

From: Carlos Simmerling via AMBER <>
Date: Sat, 3 Sep 2022 23:01:53 -0400

Can you be more specific about what you mean? Pkas for histidine in
general, or are you doing constant ph md?

On Sat, Sep 3, 2022, 9:53 PM Liao via AMBER <> wrote:

> Dear List,
> From what I read and know, for histidine, the HIE tautomer is the more
> common one on proteins, that the N3 nitrogen is the one protonated. But
> surprisingly, the pKa for the N3 is also lower, about 0.5 units less than
> N1, HID. Why is this the case? The lower pKa one should be the one that’s
> deprotonated, not the other way round. This seems quite puzzling to me. Any
> help will be appreciated, thanks.
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Received on Sat Sep 03 2022 - 20:30:02 PDT
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