Table 1.

Classification and characteristics of phytases

Source	Specific sequence properties	Active areas	Refs
Histidine acid phytases (HAPhy)	Conservative motif of the active center (RHGXRXP), conservative cysteine motif and CAP with the catalytic C-terminal dipeptide (HD)	pH 2.5–5.5	(Ullah et al. 2011; Wang et al. 2004; Wyss et al. 1998)
Cysteine phytase (Cphy)	β-fold and α-helix domain and two α-helices near the C-terminal	pH 2.5–5.5	(Kumar and Agrawal 2014; Piddington et al. 1993)
Purple acid phosphatase (PAPhy)	Motifs DXG, GDXXY, GNH [E / D], VXXH and GHXH	pH 2.5–5.5	(Devillers et al. 2003; Kyrtopoulos et al. 1985)
β-propeller phytase (BPPhy)	P-loop HCXXGXXR and a WPD loop	Neutral or alkalescence	(Chan et al. 2006; Fang et al. 2018; Viader-Salvado et al. 2010)