Barley oxalate oxidase is a hexameric protein related to seed storage proteins: evidence from X‐ray crystallography

Abstract
The oxalate oxidase enzyme expressed in barley roots is a thermostable, protease‐resistant enzyme that generates H2O2. It has great medical importance because of its use to assay plasma and urinary oxalate, and it has also been used to generate transgenic, pathogen‐resistant crops. This protein has now been purified and three types of crystals grown. X‐ray analysis shows that the symmetry present in these crystals is consistent with a hexameric arrangement of subunits, probably a trimer of dimers. This structure may be similar to that found in the related seed storage proteins.