The enzyme 4-phytase () catalyzes the following reaction:
myo-Inositol hexakisphosphate is also known as phytic acid.
These enzymes belongs to the family of hydrolases, specifically those acting on phosphoric monoester bonds. The systematic name of this enzyme class is myo-inositol-hexakisphosphate 4-phosphohydrolase. Other names in common use include 6-phytase (name based on 1-numbering system and not 1<small>D</small>-numbering) and phytate 6-phosphatase.
Enzymes of this type participate in inositol phosphate metabolism.