Purification and characterization of an aspartic protease from potato leaves.
A protease was isolated from potato (Solanum tuberosum L. cv. Pampeana) leaves 48 h after detaching, when aspartic protease (AP) activity is markedly increased. Purification was performed by ammonium sulfate precipitation, ion exchange chromatography and affinity chromatography. A size of 40 kDa was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; it is monomeric and its properties are consistent with those of aspartic proteinases (EC 3.4.23): it has a pH optimum of 3 and it is inhibited by pepstatin. Like other plant APs, leaf AP appears to be glycosylated with a complex-type N-glycan. The enzyme has properties different from those of a tuber AP previously described, indicating that they may have different physiological roles.
Guevara
María G.
MG
Instituto de Investigaciones Biológicas (IIB), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Argentina.
Daleo
Gustavo R.
GR
Oliva
Claudia R.
CR