Mechanisms of inhibition of triacylglycerol hydrolysis by human gastric lipase

Yan Pafumi, Denis Lairon, Paulette Lechene De La Porte, Christine Juhel, Judith Storch, Margit Hamosh, Martine Armand

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Abstract

In the human stomach, gastric lipase hydrolyzes only 10 to 30% of ingested triacylglycerols because of an inhibition process induced by the long chain free fatty acids generated, which are mostly protonated at gastric pH. The aim of this work was to elucidate the mechanisms by which free fatty acids inhibit further hydrolysis. In vitro experiments examined gastric lipolysis of differently sized phospholipid-triolein emulsions by human gastric juice or purified human gastric lipase, under close to physiological conditions. The lipolysis process was further investigated by scanning electron microscopy, and gastric lipase and free fatty acid movement during lipolysis were followed by fluorescence microscopy. The results demonstrate that: 1) free fatty acids generated during lipolysis partition between the surface and core of lipid droplets with a molar phase distribution coefficient of 7.4 at pH 5.40; 2) the long chain free fatty acids have an inhibitory effect only when generated during lipolysis; 3) inhibition of gastric lipolysis can be delayed by the use of lipid emulsions composed of small-size lipid droplets; 4) the release of free fatty acids during lipolysis induces a marked increase in droplet surface area, leading to the formation of novel particles at the lipid droplet surface; and 5) the gastric lipase is trapped in these free fatty acid-rich particles during their formation. In conclusion, we propose a model in which the sequential physicochemical events occurring during gastric lipolysis lead to the inhibition of further triacylglycerol lipolysis.

Original languageEnglish (US)
Pages (from-to)28070-28079
Number of pages10
JournalJournal of Biological Chemistry
Volume277
Issue number31
DOIs
StatePublished - Aug 2 2002

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Pafumi, Y., Lairon, D., De La Porte, P. L., Juhel, C., Storch, J., Hamosh, M., & Armand, M. (2002). Mechanisms of inhibition of triacylglycerol hydrolysis by human gastric lipase. Journal of Biological Chemistry, 277(31), 28070-28079. https://doi.org/10.1074/jbc.M202839200