PURIFICATION AND CIRCULAR DICHROISM STUDIES OF MULTIPLE FORMS OF ACTINIDIN FROM ACTINIDIA CHINENSIS (KIWIFRUIT)

摘要

Actinidin, a cysteine proteinase from the kiwifruit (Actinidia chinensis), is composed of multiple forms. By means of anion-exchange high-resolution liquid chromatography four actinidin isoforms were isolated as homogeneous proteins with molecular weights of 27 kDa. These enzymes possess similarities in secondary structure, as indicated by their circular dichroism (CD) spectra in the far-ultraviolet region (185-250 nm), which gave results in good agreement with those derived from previous X-ray diffraction studies of actinidin. The CD curves of the actinidin forms lacked the shoulder at 200 nm which is characteristic of papain and proteinase Omega spectra. Since the molecular structures of the three proteinases mentioned above are very similar, it is likely that spectral differences among them originate from aromatic side-chain contributions. [References: 24]