Gastric Lipases

Dog gastric lipase CaMV enhanced 35S promoter/ CaMV 35S terminator LP of rabbit gastric lipase precursor LP of sweet potato sporamin precursor N. tabacum (leaves secretion) N. tabacum (leaves vacuole) 7% of acid extractable proteins 5% of acid extractable proteins 51... 

The hydrolysis of triacylglycerol is catalysed by lipases, two of which are present in the stomach. These are lingual lipase, which is secreted by the soft palate, and gastric lipase, which is secreted by the gastric glands of the stomach. Gastric lipase is particnlarly important in the newborn since, at this stage of life, pancreatic secretions contain relatively little lipase. 

Lingnal and gastric lipases catalyse only partial lipolysis to prodnce fatty acids and diacylglycerol. 

The long-chain fatty acids stimulate the secretion of cholecystokinin, which increases secretion of gastric lipase (i.e. positive feedback). 

Various factors are required for regular fat digestion. Sublingual lipase and eventually a gastric lipase — which are both stable in an acidic environment — start digesting dietary fats in the stomach. In the intestine, pancreatic bicarbonate as well as bile acids are essential for emulsification of fats and fat-soluble substances which are then cleaved by pancreatic lipases. The cleavage products are incorporated into micelles and can then penetrate the unstirred water layer (UWL) which covers the intestinal surface. There, they can deliver the cleavage products of dietary fats as well as fat-soluble substances (e.g., carotenoids, vitamin E, vitamin A) to the luminal surface of the enterocytes. 

Most substances are not readily absorbed in the mouth or esophagus one of several exceptions is nitroglycerin, which is administered for certain heart disfunctions and absorbed if left in contact with oral tissue. The stomach is the first part of the gastrointestinal tract where substantial absorption and translocation to other parts of the body may take place. The stomach is unique because of its high content of HC1 and consequent low pH (about 1.0). Therefore, some substances that are ionic at pH values near 7 and above are neutral in the stomach and readily traverse the stomach walls. In some cases, absorption is affected by stomach contents other than HC1. These include food particles, gastric mucin, gastric lipase, and pepsin. 

Gastric lipase and pancreatic lipase are the two major triacylglyceride ester hydrolases (EC 3,1.1.3) in mammals, but they probably have no effect on the recently introduced synthetic poly glycerol esters used as emulsifiers in food and as dietetic aids (Fig, 1),... 

It is dear that the interconnection between the activities of the different lipolytic enzymes, where the first enzyme modifies the physicochemical state of the lipid substrate in such a way that it becomes available to another enzyme, is not only of prime importance for lipid digestion, but also results in a broad synergism between gastric lipase, colipase, pancreatic lipase, phospholipase As. calcium, caiboxylester Lipase, bite salts, and substrate interraecK tes [55,62-64]. 

The intragastric predigestion by gastric lipase [66] is not impaired in patients with exocrine pancreas insufficiency. For the completion of digestion in the... 

The use of gastric lipase (Table 2), if it can be done at a reasonable cost, should also be considered However, its isomeric specificity, restricted mainly to the m-3 position, makes such an approach unlikely. 

Bemback, L fiiacabcig, and G. Hcmcli. The compieie digestion of human milk triacylglyccxol In vitro requires gastric lipase, pancreatic colipase-depcndent lipase and bile salt-stimulated lipase. J. Clio. Invest. Jf5 1221 (1990). 

In the stomach, the chemicals contact other already-existing materials (stomach contents), secretions, (e.g., pepsin, gastric lipase, rennin), and hydrochloric acid. The effect of pH in the stomach, and the influence of pH on the ionization of weak organic acids and bases, plays a major role in the bioavailability of the chemical within the organism. 

Bernback, S., Blackberg, L., Hernell, O. 1989. The complete digestion of human milk triacyl-glycerol in vitro requires gastric lipase, pancreatic colipase-dependent lipase, and bile salt-stimulated lipase.. / Clin. Invest. 85, 1221-1226. 

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