zingibain, zingipain, or ginger protease (ec 3.4. 22.67) is a cysteine protease enzyme found in ginger (zingiber officinale) rhizomes. it catalyses the preferential cleavage of peptides with a proline residue at the p2 position. it has two distinct forms, ginger protease i (gp-i) and ginger protease ii (gp-ii).