| 1. |
- Barros, H., et al.
(författare)
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Hydrolysis of phosphatidylinositol by human panreatic phospholipase A2
- 1990
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 25:2, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Pure human pancreatic phospholipase A2 efficiently hydrolyzed the 2-ester bond of 14C-2-linoleoyl and 14C-2-arachidonyl phosphatidylinositol (PI). The rate of hydrolysis varied markedly with the bile salt (sodium taurocholate to sodium taurodeoxycholate, 3:4 mol/mol) concentration, the hydrolysis being decreased with increasing bile salt to PI ratio. The influence of bile salts was thus similar to that which has earlier been described for the hydrolysis of phosphatidylcholine (PC) with pig pancreatic phospholipase A2. When 2-3H-arachidonyl PC and 2-14C-arachidonyl PI were incorporated into a mixed substrate, PI was hydrolyzed even faster than PC, the hydrolysis of both phospholipids varying in the same manner with bile salt concentration. 2-14C-arachidonyl PI was also efficiently hydrolyzed by human duodenal content, although at a somewhat slower rate than 2-3H-arachidonyl PC. It is concluded that PI is a good substrate for human phospholipase A2. This minor but arachidonate-rich dietary phospholipid may thus be digested and absorbed by pathways similar to those of the major dietary and bile phospholipid, phosphatidylcholine.
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| 2. |
- Chen, Qi, et al.
(författare)
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Digestion of triacylgycerols containing longchain polyenoic fatty acids in vitro by colipase dependent lipase and human milk bile salt stimulated lipase
- 1994
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Ingår i: Biochimica et Biophysica Acta. - : Elsevier BV. - 0006-3002. ; 121:2, s. 239-243
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Tidskriftsartikel (refereegranskat)abstract
- To assess the role of human milk bile salt-stimulated lipase (BSSL) in the digestion of polyunsaturated ester bonds of triacylglycerols, hydrolysis of docosahexaenoic acid (22:6(n − 3)) ester bonds was compared to that of oleic acid (18:1(n − 9)) or arachidonic acid (20:4(n − 6)) esters. As model substrates, we used rat chylomicrons obtained after feeding human milk fat globules and radiolabeled fatty acids. Radiolabeled chylomicrons were incubated with colipase-dependent pancreatic lipase, with BSSL, or with both enzymes in combination. Both enzymes hydrolyzed 18:1 more efficiently than 22:6 esters. With colipase-dependent lipase there was a large accumulation of 22:6 in diacylglycerol whereas with BSSL it accumulated mainly in monoacylglycerol. Esters containing 20:4 were hydrolyzed by BSSL as efficiently as 18:1 but this fatty acid also accumulated as diacylglycerol with colipase-dependent lipase. At low bile salt concentrations, as found in duodenal contents of newborns, colipase-dependent lipase was virtually unable to hydrolyze esters of 20:4 and 22:6 whereas BSSL hydrolyzed these esters at appreciable rates. Combining the two enzymes gave the most efficient hydrolysis of all fatty acids tested regardless of bile salt concentrations. BSSL may thus have a physiological role in completing duodenal hydrolysis of milk triacylglycerols containing 22:6- or 20:4-esters to free fatty acids and monoacylglycerol.
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| 3. |
- Duan, Rui-Dong, et al.
(författare)
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Decrease in contents of pancreatic carboxyl ester lipase, phospholipase A2 and lingual lipase in rats with with streptozotocin-induced diabetes.
- 1993
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 28:3, s. 256-260
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Tidskriftsartikel (refereegranskat)abstract
- The changes in contents of pancreatic carboxyl ester lipase, phospholipase A2, and lingual lipase in rats with streptozotocin (STZ)-induced diabetes have been studied. The contents of pancreatic carboxyl ester lipase and phospholipase A2 decreased by 40% and 45%, respectively, 5 days after injection of STZ, whereas pancreatic lipase steadily increased to 100% over control. The content of lingual lipase decreased sharply by more than 90% 2 days after STZ injection, followed by a tendency to recover slightly. Insulin treatment at a dose abolishing the urine glucose in diabetic rats for 3 days restored the contents of pancreatic lipase, carboxyl ester lipase, and lingual lipase but not pancreatic phospholipase A2. The results indicate that lack of insulin action induces an anticoordinate change in gastrointestinal lipolytic enzymes, with decreases in pancreatic carboxyl ester lipase, phospholipase A2, and lingual lipase contents and an increase in pancreatic lipase content.
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| 4. |
- Hernell, Olle, et al.
(författare)
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Does the bile salt stimulated lipase of human milk have a role in the use of the milk long-chain polyunsaturated fatty acids?
- 1993
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Ingår i: Journal of Pediatric Gastroenterology and Nutrition - Jpgn. - 1536-4801 .- 0277-2116. ; 16:4, s. 426-431
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Tidskriftsartikel (refereegranskat)abstract
- Long-chain polyunsaturated (LCP) fatty acids derived from linoleic (18:2 n-6) and alpha-linolenic (18:3 n-3) acids are considered essential nutrients in preterm infants. The efficiency by which such fatty acids are released as absorbable products from triacylglycerol was explored in vitro using rat chylomicron triacylglycerol as substrate. When incubated with purified human pancreatic colipase-dependent lipase and colipase, arachidonic acid (20:4 n-6) was released less efficiently than linoleic acid from such triacylglycerol. This difference was not seen when purified human milk bile salt-stimulated lipase (BSSL) was incubated with the triacylglycerol substrate, and it was almost abolished when colipase-dependent lipase (with colipase) and BSSL acted simultaneously, as they do in breast-fed infants. There was no difference in arachidonic acid and eicosapentaenoic acid (20:5 n-3) release rates with either colipase-dependent lipase or BSSL, albeit the release was more rapid with the milk enzyme than with colipase-dependent lipase. Again, the most efficient release as absorbable free fatty acids was achieved when the two lipases operated together. The relative resistance to hydrolysis of arachidonic acid and eicosapentaenoic acid by colipase-dependent lipase was best explained by the localization of the first double bond to the delta-5 position of the respective fatty acid. The results obtained suggest that BSSL is of importance for the efficient use of human milk LCP fatty acids.
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