FIG. 2.

Purification of prodrug hydrolase. (A) Anion-exchange chromatography. PBMC extract from 15 × 10⁹ cells (75 to 85 ml) was diluted 1:10 (vol/vol) with Q15 buffer A and loaded onto an anion-exchange column. Bound protein was eluted and assayed for both GS-7340 and GS-9131 hydrolase activity as described in the text. (B) Hydrophobic interaction chromatography. The Q15 pool was processed as described in the text and loaded onto a butyl Sepharose HIC column. Bound protein was eluted and assayed for prodrug hydrolase activity. Symbols: •, GS-7340 hydrolase activity; ○, GS-9131 hydrolase activity; ---, salt concentration gradient. c, concentration.