Characterization of gastric lipolytic activity
| Autor: | Robert Goldstein, Emile Levy, Eleazar Shafrir, Serem Freier |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
Male
Taurocholic Acid Lipolysis Biophysics Biochemistry Substrate Specificity Endocrinology Tongue medicine Animals Gastric lipase Lipase Pancreas Triglycerides Lipoprotein lipase Taurodeoxycholic Acid biology Chemistry Stomach digestive oral and skin physiology Hydrogen-Ion Concentration Rats Pentagastrin Enzyme Activation medicine.anatomical_structure biology.protein Duodenum Female Lingual lipase medicine.drug |
| Zdroj: | Biochimica et biophysica acta. 664(2) |
| ISSN: | 0006-3002 |
| Popis: | A lipase activity of gastric origin was demonstrated by in vivo cleavage of medium and long-chain triacylglycerol substrates in the stomach of newborn rats with ligated pylorus and oesophagus and excised pancreas and lingual glands. The release of lipase activity from stomach tissue slices was also shown on in vitro incubation with histamine or pentagastrin. Distinctive differences were found in the properties of gastric lipase (EC 3.1.1.3) when compared with lipases from serous lingual glands and pancreas in homogenates of the corresponding tissues, using trioleylglycerol as substrate and albumin as tree fatty acid acceptor. The optimal pH of the lipases was 6.8, 5.8 and 9.2, respectively. Pancreatic lipase activity remained unchanged in the presence of taurocholate and taurodeoxycholate (2–10 mmol/l), whereas gastric and lingual lipases became activated. Deoxycholate activated the gastric lipase, but inactivated the lingual and pancreatic lipases. Lingual lipase was moderately activated at low concentrations of Triton X-100, whereas the other lipases were inhibited by this non-ionic detergent. With dl -glyceryl-1-palmitate-2-oleate-3 stearate as substrate, the oleate ester bond in the sn-2 position was split approx. 33% by gastric lipase and 22% by lingual lipase, and only 8% by pancreatic lipase at optimal pH of those enzymes. Similar differences were obtained also when this substrate was cleaved at pH 7.0 by the three lipases. Substantial cleavage of the sn-2 position by the gastric and lingual lipases was also shown with 1,2-di- and 2-monooleylglycerol substrates. Further differences were noted in the subcellular localization of the enzymes: gastric lipase activity was mostly associated with the microsomal, the lingual with the cytoplasmic and the pancreatic lipase with the heavy subcellular fractions. These properties indicate that gastric lipase is a separate enzyme entity which may participate in fat digestion during the postnatal period in the moderately acid stomach milieu and then in the duodenum, upon activation with bile salts. |
| Databáze: | OpenAIRE |
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