Purification of Human Pancreatic Lipase and the Influence of Bicarbonate on Lipase Activity

Abstract

Pancreatic lipase was purified from human pancreatic juice by ion exchange chromatography and HPLC molecular sieve chromatography. The molecular weight was measured as 50 Kda by SDS-PAGE, as 47 Kda by HPLC and was calculated as 51 Kda following amino acid analysis. The isoelectric point of the purified lipase was 7 · 4 and maximal enzyme activity occurred at pH 9 · 5 in glycine buffer (0 · 1 mol/L) containing deoxycholate (19 mmol/L), colipase (3 mg/L) and triolein (0 · 3 mmol/L). However, the addition of bicarbonate at a final concentration of 0 · 1 mol/L decreased the pH for maximal enzyme activity and increased the lipase activity significantly. At higher concentrations of bicarbonate the lipase activity decreased. These results suggest that bicarbonate is an important regulator of lipase activity, perhaps related to an effect on the detergent properties of deoxycholate.