The CHAD domain is an alpha-helical domain functionally associated with the Pfam:PF01928 domains. It has conserved histidines that may chelate metals [1].

1: The catalytic domains of thiamine triphosphatase and CyaB-like adenylyl cyclase define a novel superfamily of domains that bind organic phosphates. Iyer LM, Aravind L; BMC Genomics 2002;3:33-33. PMID:12456267