Figure 5

Separation of aminopeptidase and Tau-cleaving activities on an S-200 column. (a). PSA derived from Sf9 cells was purified as described in Methods. Following an anionic QMA column, the enzyme was chromatographed on an S-200 column and fractions were assayed for both Tau and aminopeptidase activity. The arrows show the eluted PSA activity detected on the gel. Tau activity is shown as the % hydrolysis (solid square), while aminopeptidase activity toward alanine 4-MNA is shown by solid triangles. (b). An Sf9 cell extract from non infected cells was fractionated the same way as the above. Upper panel: Fractions assayed for Tau-cleaving activity. Lower panel: Fractions assayed for Tau-cleaving activity in the presence of exogenous C-His₆-PSA with a molar ratio of Tau:PSA (5:1).