This is the catalytic region of the superfamily of enzymes referred to as GH36. UniProtKB:Q76IQ9 is a chitobiose phosphorylase that catalyzes the reversible phosphorolysis of chitobiose into alpha-GlcNAc-1-phosphate and GlcNAc with inversion of the anomeric configuration. The full-length enzyme comprises a beta sandwich domain and an (alpha/alpha)(6) barrel domain. The alpha-helical barrel component of the domain, this family, is the catalytic region.