Enzyme activity of human carboxylesterases.

<p>Plots of initial rates of reaction against enzyme concentration assayed as described in the Methods section at a substrate concentration of 750 μM 4-NPA (a) CES1 (b) CES1 N79Q. Plots of initial reaction rates against substrate concentration for the hydrolysis of 4-NPA by (c) hCES1 and (d) hCES1 N79Q (3.4 nM each enzyme). The molarity of the enzyme was calculated assuming 100% trimer with a molecular weight of 182.7 kDa.</p

Purification of human carboxylesterases.

<p>(a) Size exclusion profiles of purified hCES1 (blue trace) hCES1 N79Q (green trace) and hCES1 S221A (red trace) enzymes from media of transfected HEK cells. Samples were run on a HiLoad 16/60Superdex 200 column (GE Healthcare) in 200 mM NaCl, 20 mM Tris-HCl, pH 7.5. The peak corresponds to a molecular weight of approximately 160 kDa as estimated from the elution volumes of globular proteins of known molecular weight: Aprotinin (6.5 kDa) Ribonuclease A (13.7 kDa) Carbonic Anhydrase (29 kDa), Ovalbumin (44 kDa), Conalbumin (75 kDa) Aldolase (158 kDa) Ferritin (440 kDa) and Blue Dextran 2000. (b) SDS-polyacrylamide gel of purified CES1 (lanes 1 and 2) and CES1 N79Q (lanes 3 and 4) untreated (lanes 1 and 3) and treated with PNGaseF (lanes 2 and 4). (c) The sedimentation velocity distribution for hCES1 N79Q. Data for hCES1 and hCES1 S221A gave the same profiles.</p