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. Author manuscript; available in PMC: 2011 Mar 1.
Published in final edited form as: Antiviral Res. 2009 Dec 5;85(3):482–489. doi: 10.1016/j.antiviral.2009.12.003

Table I.

Partial purification scheme of APP-S from Caco-2 cells. Caco-2 cell homogenate was sequentially purified by ammonium sulfate precipitation, bestatin affinity chromatography, and MonoQ anion exchange chromatography. Following each purification step, the active fraction was incubated with Val-Ser-cHPMPC at 37 °C (10 mM sodium phosphate buffer, pH 7.4) with aliquots taken at predetermined time points (3-30 min). Disappearance of the prodrug peak was monitored by HPLC (detection at 274 nm) and used to calculate specific activity (nmol/min·mg protein) and half-life (min).

Purification step Total protein Specific activity Half-life of Val-Ser-cHPMPC Purification
mg nmol/min·mg protein min -fold
Cytosolic fraction 174 6.8 13.6 1.0
(NH4)2SO4 precipitation 55 11.2 7.2 1.7
Bestatin column 5.1 ND a ND ND
MonoQ column 0.8 142.5 4.6 22
a

ND = not determined