The radical of histidine produced by removal of a hydrogen from a nitrogen atom; prefixed by Na, Nτ, or Nπ. ... (05 Mar 2000) ... 
(—His) Type: Term Pronunciation: his′ti-din-ō Definitions: 1. The radical of histidine produced by removal of a hydrogen from a nitrogen atom; prefixed by Nα, Nτ, or Nπ.