<p>(A) and (B) compare the TBBL- and <i>δ</i>-val-hydrolyzing activity of the rh-PON1 enzymes, respectively. The TBBL-hydrolyzing activity was determined using Ellman-based colorimetric assay. Equal amounts of the rh-PON1 enzymes were separately incubated with 0.5 mM TBBL in the activity buffer containing 0.3 mM DTNB and the hydrolysis of TBBL was monitored at 412 nm. The <i>δ</i>-val-hydrolyzing activity of the rh-PON1 enzymes was determined by pH-indicator assay. The enzymes were incubated with 1 mM (in 50 mM bicine buffer pH 8.3, 1 mM CaCl<sub>2</sub>) and the hydrolysis of <i>δ</i>-val was monitored at 577 nm using <i>m</i>-cresol purple as the indicator. The hydrolytic activity of rh-PON1<sub>(wt)</sub> was taken 100% and the percentage activities of all the rh-PON1 mutants were calculated. Enzymatic assays were performed in duplicate. Various mutants were named with single letter code representing the particular amino acid at position 192. <b>Legends:</b> same as in the legends of Fig 3.</p
