The affinities of procolipase and colipase for interfaces are regulated by lipids.
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.
Schmit
G D
GD
Hormel Institute, University of Minnesota, Austin 55912, USA.
Momsen
M M
MM
Owen
W G
WG
Naylor
S
S
Tomlinson
A
A
Wu
G
G
Stark
R E
RE
Brockman
H L
HL
D000327:Adsorption; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002250:Carbon Radioisotopes; D003089:Colipases / Q000737:chemistry* / Q000494:pharmacology*; D004075:Diglycerides; D004792:Enzyme Precursors; D005231:Fatty Acids, Unsaturated; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D008055:Lipids; D010713:Phosphatidylcholines; D011498:Protein Precursors / Q000737:chemistry* / Q000494:pharmacology*; D014357:Trypsin
D002250:Carbon Radioisotopes; D003089:Colipases; D004075:Diglycerides; D004792:Enzyme Precursors; D005231:Fatty Acids, Unsaturated; D008055:Lipids; D010713:Phosphatidylcholines; D011498:Protein Precursors; C027891:1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine; C037107:procolipase; C078401:13,16-docosadienoic acid; D008049:Lipase; D014357:Trypsin; C013965:diolein