AMBER Archive (2009)

Subject: [AMBER] Histidine, which form?

Date: Mon Jun 15 2009 - 09:54:05 CDT

For Histidine, there are three forms of it, HIE, HID, and HIP.
Delta poistion is position number 1 and Epsilon Position is position number 3.
The problem is that:
There two different systems of numbering the atoms in the
imidazole ring of histidine had both been used for a considerable time (biochemists
generally numbering as 1 the nitrogen atom adjacent to the side chain, and organic chemists
designating it as 3).

So, could you tell me which nitrogen atom is the delta one, please?
Also, could you give me an example of HIP when histidine is protonated on both positions, please?

Thanks in Advance

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