GZMH, as known as granzyme H isoform 1, is a member of the granzyme family of serine proteases found specifically in the granules of cytotoxic Tlymphocytes (CTL) and natural killer (NK) cells. The more abundant expression of this protein than granzyme B in NK cells suggests that granzyme H may complement the pro-apoptotic function of granzyme B in this cell type. Recombinant human GZMH, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.