Pentonolactonase involved in D-arabinose and D-xylose catabolism. Catalyzes the hydrolysis of both L-arabino-gamma-lactone and D-xylono-gamma-lactone to the corresponding acids. Can also hydrolyze D-galactono-gamma-lactone and D-glucono-delta-lactone. H2O + L-arabinono-1,4-lactone = H(+) + L-arabinonate D-xylono-1,4-lactone + H2O = D-xylonate + H(+) Binds 1 divalent metal cation per subunit (By similarity). Most active with Co(2+), Mg(2+) or Mn(2+). Has weaker activity with Fe(2+), Ni(2+) or Zn(2+) (PubMed:28854683). Carbohydrate degradation. Monomer. Transcriptionally up-regulated by both L-arabinose and D-xylose via the pentose-specific regulator XacR. Deletion mutant shows restricted growth on L-arabinose but grows on D-xylose as the wild type. Belongs to the SMP-30/CGR1 family.