Autoproteolytic processing of aspartic proteinase from sunflower seeds

Abstract

The autoproteolytic processing of mature aspartic proteinase from sunflower seeds was investigated. The mature aspartic proteinase (48 kDa) was processed at N65s-D66s in the plant-specific region of the enzyme to form 34-kDa and 14-kDa subunits. The next step was the hydrolysis of the A25s-Q26s and N97s-E98s bonds to form a 39-kDa enzyme that consisted of 29-kDa and 9-kDa disulfide-bonded subunits. Finally, bonds including Vls-M2s, M2s-S3s, C100s-D101s, and D101s-R102s were cleaved to form non-covalently bound subunits (29 kDa and 9 kDa) by eliminating the disulfide bonds in the plant-specific region of the protein.