Purification and Properties of a Cysteine Proteinase Occurring in Dormant Wheat Seeds

Abstract

A cysteine proteinase was purified from dormant seeds of wheat (Triticum aestivum, cultivar Norin 61) and its molecular mass was estimated to be about 23kDa by gel filtration. The K_m of this proteinase at pH 5.5 was calculated as 2 μM for Z-Phe-Arg-MCA, and its activity was inhibited by cysteine proteinase inhibitors including antipain, E-64, and leupeptin. Oryzacystatin-I, a proteinaceous cysteine proteinase inhibitor in rice seeds, also inhibited its activity.