[gmx-users] Option:Coupled to heme

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Dear users,

When I use the -his option of pdb2gmx for deprotonated the Histidine residue, I get the following options:
 0. H on ND1 only (HISA) 
 1. H on NE2 only (HISB)
2. H on ND1 and NE2 (HISH) 
3. Coupled to Heme (HIS1)
Where option 3 is deprotonated. But it is named as a 'Coupled to heme'. Why option 3's name is not deprotonated HIS?

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