The name of this superfamily has been modified since the most recent official CATH+ release (v4_2_0). At the point of the last release, this superfamily was named:"
The N-terminal nucleophile aminohydrolase (Ntn) domain consists of two catalytic groups - a proton donor and a nucleophile. This superfamily consists of the nucleophile catalytic domain or Ntn hydrolase domain. The amino acid residue (cysteine in GAT, serine in penicillin acylase, and threonine in proteasome) that initiates the nucleophilic attack at the carbonyl group is located at the N-terminus of this domain. The Ntn fold domain comprises four layers of alpha-helices and beta-sheets in an alpha-beta-beta-alpha sandwich structural motif. Ntn hydrolases have divergent sequences, but share a common enzyme mechanism.
A well-characterised enzyme containing this domain is CAD, a cephalosporin acylase from Pseudomonas diminuta. It consists of an alpha-subunit with 169 residues and a beta-subunit with 520 residues. The enzyme is described as a bowl-shaped molecule with two knobs attached to the bowl, facing each other. The alpha-beta-beta-alpha motif is the central part of the molecule. Ser-1, the N-terminal residue of the beta subunit is invariant and known to play a critical role in both autoproteolytic activation and enzyme catalysis.
|Domain clusters (>95% seq id):||87|
|Domain clusters (>35% seq id):||41|
|Structural Clusters (5A):||7|
|Structural Clusters (9A):||4|