Involved in phosphonate degradation. (2-aminoethyl)phosphonate + pyruvate = L-alanine + phosphonoacetaldehyde H2O + phosphonoacetaldehyde = acetaldehyde + H(+) + phosphate Binds 1 Mg(2+) ion per subunit. Homodimer. In the N-terminal section; belongs to the HAD-like hydrolase superfamily. PhnX family. In the C-terminal section; belongs to the class-V pyridoxal-phosphate-dependent aminotransferase family. PhnW subfamily.