HpaII (IntEnz: EC 184.108.40.206) is a restriction enzyme obtained from the microorganism called Haemophilus parainfluenzae. It is a DNA restriction enzyme, therefore it has the ability to cut the DNA from certain region as demonstrated below. It has the ability to produce cohesive ends, which are rather useful in constructing plasmids.
HpaII enzyme can cleave a DNA only when C is protected by methylation. This feature is exploited for determination of the clonal origin of a mammalian female tumor through HUMARA assay.