Poly(aspartate) (PAA) is a bio-based, biocompatible, biodegradable alternative to polycarboxylate of poly(acrylate). Bacterial PAA-hydrolyzing enzyme can also perform synthesis of poly(alpha-ethyl beta-aspartate). This family is close to PHB depolymerase. The LpqC, poly(3-hydroxybutyrate) depolymerase from Bordetella parapertussis (CASP Target) (structure 3D0K) belongs to this family. Polyaspartic acid (PASA) is also a natural polymer as fragment of larger proteins with length up to 50 amino acids. Synthetic tPAA(thermally synthesized PAA) consists of beta-amide (70%) and alpha-amide,(30%) D- and L-aspartate units; the alpha- and beta-amide units are randomly distributed. PAA hydrolase-1 is an alpha beta hydrolase inhibited by PMSF and DFP. PAA hydrolase-2 is closer to metallo carboxypeptidase inhibited by DFP and PMSF