Lipases in Milk

Olivecrona, Thomas; Vilaró, Senén; Olivecrona, Gunilla

doi:10.1007/978-1-4419-8602-3_12

Cited by 32 publications

(26 citation statements)

References 92 publications

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“…Despite early research suggesting otherwise (Downey & Andrews, 1969), it is now accepted that only one lipolytic enzyme, lipoprotein lipase (LPL), accounts for most, if not all, of the lipolytic activity in bovine milk (Olivecrona, 1980;Olivecrona, Vilaro, & Olivecrona, 2003). This is not the case for human milk, which contains a bile-saltstimulated lipase in addition to LPL.…”

Section: Milk Lipasementioning

confidence: 96%

Lipoprotein lipase and lipolysis in milk

Deeth

2006

International Dairy Journal

228

157

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Section: Milk Lipasementioning

confidence: 96%

Lipoprotein lipase and lipolysis in milk

Deeth

2006

International Dairy Journal

228

157

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“…In an experiment to assess the glycosylation pattern, the time was reduced to 30 min. Immunoprecipitations were performed with a rabbit antiserum against LPL that had been purifi ed from human milk by chromatography on heparinSepharose and on N-desulfated, N-acetylated heparin coupled to Sepharose ( 9,32 ). A corresponding preimmune serum was used as a control.…”

Section: Met Incorporation and Immunoprecipitationmentioning

confidence: 99%

“…The enzyme has no known function in milk or in the intestines of nursing offspring. LPL in the milk is bound to casein micelles or to milk fat droplets and can be found on fat droplets in secretory vesicles, but the enzyme does not hydrolyze the milk lipids ( 9 ). That LPL levels were normal in milk, but very low in postheparin plasma, strongly suggests that entry of LPL into milk, unlike entry of LPL into the capillary lumen, is independent of GPIHBP1.…”

Section: Cell Expression and Lpl Binding Properties Of Gpihbp1 Mutantsmentioning

confidence: 99%

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Mutation of conserved cysteines in the Ly6 domain of GPIHBP1 in familial chylomicronemia

Olivecrona¹,

Ehrenborg

Semb³

et al. 2010

Journal of Lipid Research

109

103

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Supplementary key words compound heterozygote • lipoprotein lipase • milk lipids • mammary gland • glycosylphosphatidylinositolanchored high density lipoprotein-binding protein 1 • endothelial cells LPL hydrolyzes triglycerides in plasma lipoproteins, making fatty acids available for use in cells ( 1,2 ). LPL also mediates the binding of lipoproteins to cell surfaces and receptors (3)(4)(5). Reduced LPL activity from mutations in LPL or its cofactor apolipoprotein CII lead to a striking accumulation of triglyceride-rich lipoproteins in the plasma (type I hyperlipoproteinemia) ( 6 ). Clinical symptoms and signs include abdominal pain with or without pancreatitis, eruptive xanthomas, and hepatosplenomegaly. Recently, mutations in the gene for apolipoprotein AV have been uncovered in some patients with unexplained chylomicronemia ( 7 ).LPL is synthesized primarily in parenchymal cells in skeletal muscle, heart, and adipose tissue ( 1, 2 ) but then fi nds its way into the lumen of capillaries, where it participates in the processing of the plasma lipoproteins. LPL is also synthesized in the mammary gland and appears in breast milk after parturition ( 8,9 ). Its function within the milk is unknown, but there is little doubt that LPL-mediated processing of lipoproteins within the capillaries of the mammary gland is important for providing the lipid nutrients to produce milk fat.Abstract We investigated a family from northern Sweden in which three of four siblings have congenital chylomicronemia. LPL activity and mass in pre-and postheparin plasma were low, and LPL release into plasma after heparin injection was delayed. LPL activity and mass in adipose tissue biopsies appeared normal. [ 35 S]Methionine incorporation studies on adipose tissue showed that newly synthesized LPL was normal in size and normally glycosylated. Breast milk from the affected female subjects contained normal to elevated LPL mass and activity levels. The milk had a lower than normal milk lipid content, and the fatty acid composition was compatible with the milk lipids being derived from de novo lipogenesis, rather than from the plasma lipoproteins. Given the delayed release of LPL into the plasma after heparin, we suspected that the chylomicronemia might be caused by mutations in GPIHBP1 . Indeed, all three affected siblings were compound heterozygotes for missense mutations involving highly conserved cysteines in the Ly6 domain of GPIHBP1 (C65S and C68G). The mutant GPIHBP1 proteins reached the surface of transfected Chinese hamster ovary cells but were defective in their ability to bind LPL (as judged by both cell-based and cell-free LPL binding assays). Thus, the conserved cysteines in the Ly6 domain are crucial for GPIHBP1 function.

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“…Besides its potential role as carrier for LPL, HS has been suggested to act as a chaperone keeping the enzyme active during the passage from the site of synthesis to the site of action (9). Studies with cells deficient in HS showed, however, that HS is not required for the intracellular processing and secretion of LPL (10). Secretion of LPL to the culture medium from HS-deficient cells was even higher than from wild type cells, which is in line with that HS may also have a role as co-receptor in internalization and catabolism of LPL (11)(12)(13)(14).…”

Section: Heparan Sulfates (Hs)mentioning

confidence: 99%

Isolation and Characterization of Low Sulfated Heparan Sulfate Sequences with Affinity for Lipoprotein Lipase

Spillmann

Lóokene

Olivecrona

2006

Journal of Biological Chemistry

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Lipoprotein lipase (LPL), which is an important enzyme in lipid metabolism, binds to heparan sulfate (HS) proteoglycans. This interaction is crucial for several aspects of LPL function, such as intracellular/extracellular transport and high capacity attachment to cell surfaces. Retention of LPL on the capillary walls, and elsewhere, via HS chains is most likely affected by the quality and quantity of HS present. Earlier studies have demonstrated that LPL interacts with highly sulfated HS and heparin oligosaccharides. Since such structures are relatively rare in endothelial HS, we have re-addressed the question of physiological ligand structures for LPL by affinity purification of endlabeled oligosaccharides originating from heparin and HS on immobilized LPL. By a combination of chemical modification and fragmentation of the bound material we identified that the bound fraction contained modestly sulfated oligosaccharides with an average sulfation of one O-sulfate per disaccharide unit and tolerates N-acetylated glucosamine residues. Therefore LPL, containing several clusters of positive charges on each subunit, may constitute an ideal structure for a protein that needs to bind with reasonable affinity to a variety of modestly sulfated sequences of the type that is abundant in HS chains.

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Lipases in Milk

Cited by 32 publications

References 92 publications

Lipoprotein lipase and lipolysis in milk

Lipoprotein lipase and lipolysis in milk

Mutation of conserved cysteines in the Ly6 domain of GPIHBP1 in familial chylomicronemia

Isolation and Characterization of Low Sulfated Heparan Sulfate Sequences with Affinity for Lipoprotein Lipase

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