Human gastric lipase. The effect of amphiphiles

Abstract

Human gastric lipase (HGL) activity on tributyrin emulsion was detected only in the presence of amphiphiles such as bile salts, proteins (serum albumin, B-lactoglobulin or ovalbumin) or phosphatidylcholine. These findings are contrary to the strong inhibitory effect of amphiphiles observed on pure pancreatic lipase. To reveal HGL activity, amphiphiles should be added prior to HGL. This may prevent irreversible interfacial denaturation. HGL activity was found to be restricted to a triacylglycerol/water surface tension ranging from 8 dyn/cm to 13 dyn/ cm. All amphiphiles, which decrease the interfacial tension below 8 dyn/cm, act as irreversible inhibitors of HGL in the absence and in the presence of bile salts.Our results confirm that HGL is capable of hydrolysing triacylglycerol in the presence of the physiological concentration of bile salts prevailing in the upper small intestine and in the presence of alimentary proteins. These observations could explain the high dietary lipid absorption observed under pancreatic lipase deficiency.

In Vitro Gastrointestinal Digestibility of Soybean Oil-in-Water Emulsion Droplets Stabilized by Polyglycerol Esters of Fatty Acid

“…Lipase can adsorb to oil-water interfaces both in the absence or presence of bile salts. Gargouri et al (1983Gargouri et al ( , 1986 reported that the addition of bile salts to the emulsions promotes the adsorption of lipase and increases its activity. In stage IV, the emulsion droplets exhibited more negative charges.…”

Adsorption of gastric lipase onto multicomponent model lipid monolayers with phase separation

“…Most lipolytic enzymes, including gastric lipase, are irreversibly denatured and inactivated when they bind a lipid/water interface at high surface tension/low surface pressure [4]. Their activity can be preserved by lowering surface tension with amphiphiles like proteins and bile salts [57,58]. The lipase itself can play this role if sufficient amounts of the enzyme are added.…”

Les lipases du tractus digestif

“…Au contraire, ces mêmes sels biliaires semblent agir comme activateurs de la lipase gastrique humaine lorsque l'on utilise de la tributyrine comme substrat (Hamosh, 1984 ;Tiruppathi et Balasubramanian, 1982, fig. 1 (De Caro et al, 1981, Verger, 1984 Les différences dans la résistance à la dénaturation interfaciale de lipases d'origines diverses peuvent permettre d'expliquer les effets opposés des amphiphiles sur l'activité de l'enzyme gastrique par rapport à l'enzyme pancréatique (Gargouri et al, 1983(Gargouri et al, , 1984a(Gargouri et al, , 1984b(Gargouri et al, , 1986aKlein et al, 1967 ;Patton et Carey, 19811. (Hamosh, 1984, Muller et al, 1975 (Gargouri et al, 1984a (Gargouri et a/., 1986b). Il est actuellement admis que la lipolyse intragastrique génère principalement des acides gras libres et des diglycérides (Hamosh et al, 1975(Hamosh et al, , 1978 (Hamosh et al, 1975(Hamosh et al, , 1978.…”