The affinities of procolipase and colipase for interfaces are regulated by lipids

Abstract

It has been suggested that at physiological pH, the trypsin-catalyzed activation of the lipase cofactor, procolipase, to colipase has no consequence for intestinal lipolysis and serves primarily to release the N-terminal pentapeptide, enterostatin, a satiety factor (Larsson, A., and C. Erlanson-Albertsson 1991. The effect of pancreatic procolipase and colipase on pancreatic lipase activation. Biochim. Biophys. Acta 1083:283-288). This hypothesis was tested by measuring the adsorption of [14C]colipase to monolayers of 1-stearoyl-2-oleoyl-sn-3-glycerophosphocholine and 13, 16-cis, cis-docosadienoic acid in the presence and absence of procolipase. With saturating [14C]colipase in the subphase, the surface excess of [14C]colipase is 29% higher than that of procolipase, indicating that colipase packs more tightly in the interface. With [14C]colipase-procolipase mixtures, the proteins compete equally for occupancy of the argon-buffer interface. However, if a monolayer of either or both lipids is present, [14C]colipase dominates the adsorption process, even if bile salt is present in the subphase. If [14C]colipase and procolipase are premixed for > 12 h at pH approximately 8, this dominance is partial. If they are not premixed, procolipase is essentially excluded from the interface, even if procolipase is added before [14C]colipase. These results suggest that the tryptic cleavage of the N-terminal pentapeptide of procolipase may be of physiological consequence in the intestine.

Peripheral Protein Adsorption to Lipid-Water Interfaces: The Free Area Theory

“…The purification of water and preparation of solvents, buffer, and lipid solutions have been previously described in Momsen et al (10). Porcine colipase used in this study was prepared and converted to [ 14 C]colipase by reductive methylation as described previously in Schmit et al (11). The [ 14 C]colipase had a specific radioactivity of 9.76 Ci/mol.…”

Inhibition of lipases by ∊-polylysine

“…HPL(S153G) and -polylysine were radiolabeled by reductive methylation as described for porcine colipase (14). The ratios of reagents were adjusted to compensate for the different number of free amino groups in the three proteins.…”

How Colipase−Fatty Acid Interactions Mediate Adsorption of Pancreatic Lipase to Interfaces

“…Before use the papers were cleaned by washing them sequentially with chloroform/ methanol (2:1 v/v), chloroform, and hexane, followed by airdrying at 150 °C for 50 min (40). Procolipase was purified from porcine pancreas and converted to colipase and to [ 14 C]colipase with a specific radioactivity of 21 dpm/pmol as reported elsewhere (35). PTL (triacylglycerol acylhydrolase, EC 3.1.1.3) was purified from an extract of porcine pancreas using conventional techniques as previously described (41).…”

“…Moreover, it has been shown that the clustering of Ca 2+ soaps of fatty acids enhances the adsorption of pancreatic lipase to interfaces (34). To help understand these effects, our laboratory investigated the interaction of colipase with monomolecular films of diacylphosphatidylcholine, free fatty acid, acylglycerols, and their mixtures (35,36). Based on data obtained in vivo, but in contrast to most of the earlier studies of PTLcolipase function, colipase-lipid interactions were characterized thermodynamically at a pH consistent with that in the intestinal lumen (37) and in the absence of calcium ion (38).…”