Inhibition of lipolysis in bovine milk by proteose peptone

1981 ◽  
Vol 48 (2) ◽  
pp. 247-252 ◽  
Author(s):  
Malcolm Anderson
Keyword(s):  
Blood Serum ◽  
Lipoprotein Lipase ◽  
Bovine Milk ◽  
Effective Inhibitor ◽  
In Vitro Activity ◽  
Bovine Blood ◽  
Proteose Peptone ◽  
Mechanism Of Inhibition ◽  
Total Milk

SummaryThe ability of total milk proteose peptone and individual proteose peptone components to inhibit lipolysis in milk was examined. Proteose peptone (1·5 mg/ml) when added to milk inhibited lipolysis, and component 3 was a more effective inhibitor than component 5 or component 8-fast. Inhibition by proteose peptone also occurred when the milk was treated with between 2 and 20% v/v bovine blood serum or with 5 μg/ml heparin. In vitro activity of milk lipoprotein lipase and its stability were not affected by proteose peptone. It was concluded that proteose peptone does not interact with lipase or its activator and that the mechanism of inhibition involves the substrate.

Factors affecting the distribution of lipoprotein lipase activity between serum and casein micelles in bovine milk

1982 ◽  
Vol 49 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Malcolm Anderson
Keyword(s):  
Blood Serum ◽  
Lipoprotein Lipase ◽  
Post Partum ◽  
Bovine Milk ◽  
Casein Micelles ◽  
Factors Affecting ◽  
Milk Serum ◽  
Heparin Treatment ◽  
Micellar Casein ◽  
Consistent Increase

SUMMARYThe influence of mastitis and early lactation, and the effect of treating milk with heparin, blood serum and trypsin, on the proportion of lipoprotein lipase (LPL) activity in milk serum was investigated. The relative importance of milk serum LPL and LPL bound to micellar casein in promoting lipolysis was also examined. Colostrum contained LPL activity, 45% of which was found in the serum phase in samples obtained from the first milking post partum, but this value fell to 34% in samples taken 24 h later. The proportion of serum LPL was also increased in milks from quarters infected with Staphylococcus aureus, but not after overnight treatment of normal milk at 4 °C with 5% (w/v) blood serum or 2 µg/ml trypsin. The addition of 5 µg/ml heparin resulted in a consistent increase in serum LPL which varied between 14 and 50% of total milk LPL. Heparin did not release all the enzyme bound to casein micelles even after a second heparin treatment of resuspended micelles. Serum LPL was more effective in promoting lipolysis and was more responsive to blood serum activation than LPL bound to casein micelles. Lipolysis increased after heparin treatment but the increase was not related to serum LPL activity.

scholarly journals Clearance from plasma of lymph chylomicrons and chylomicron remnants labelled with 125I-tyramine-cellobiose

1992 ◽  
Vol 286 (3) ◽  
pp. 937-943 ◽  
Author(s):  
H L Ly ◽  
B C Mortimer ◽  
E Baker ◽  
T G Redgrave
Keyword(s):  
High Density Lipoprotein ◽  
Lipoprotein Lipase ◽  
Bovine Milk ◽  
Density Lipoprotein ◽  
High Density ◽  
Low Density ◽  
Apolipoprotein B48 ◽  
Chylomicron Remnants

The aims of the present study were to evaluate the metabolism of chylomicrons (CM) and of CM remnants after labelling with radioactive iodine and converting the iodinated CM into remnants in vitro. Lymph CM were radiolabelled with 125I or sham-labelled with 127I by either the ICl procedure or the tyramine-cellobiose (TC) procedure, then injected into rats. The clearance from plasma of the iodinated CM was compared with control non-iodinated lipid-labelled CM. After iodination with ICl, the plasma removal of endogenously labelled CM was significantly different from non-iodinated CM, with increased uptake of CM triacylglycerols by the liver. In contrast, the clearances from plasma and the uptake by organs of radiolabelled lipids of CM iodinated by the TC method (TC-CM) were similar to control CM. About 40% of the label from 125I-TC-CM was insoluble in 50% propan-2-ol, indicating association with CM apolipoprotein B48. Only about 8% of label was lipid soluble, mostly in phosphatidylethanolamine. Radioactivity from 125I-TC-CM injected intravenously in rats was cleared rapidly and by 30 min only 20% remained in plasma, whereas 48% was recovered in the liver. After fractionation of the plasma by density-gradient ultracentrifugation, most label remained associated with d (relative density) less than 1.006 lipoproteins. In intact rats label was also found associated with the low-density and high-density lipoprotein fractions of plasma. When the liver was excluded from circulation, the recovery of label in low-density- and high-density-lipoprotein fractions was greatly decreased. CM remnants were prepared in vivo by injecting 125I-TC-CM into functionally hepatectomized donors and compared with remnants prepared in vitro by incubation with purified bovine milk lipoprotein lipase. Although remnants prepared in vitro cleared from plasma slower than remnants prepared in vivo, the size, lipid composition and apolipoprotein profile on gradient PAGE of the remnants were similar. We conclude that labelling of CM by the TC method avoided the ‘artefactual’ changes in metabolism seen after labelling by the ICl procedure. CM remnants when prepared in vitro using lipoprotein lipase were found to be similar to those prepared in vivo after injection into functionally hepatectomized rats.

scholarly journals The effect in vitro of high-density lipoprotein on hydrolysis of triacylglycerol by lipoprotein lipase

1981 ◽  
Vol 200 (2) ◽  
pp. 453-456 ◽  
Author(s):  
M P Rogers ◽  
I Hutchinson
Keyword(s):  
Adipose Tissue ◽  
High Density Lipoprotein ◽  
Lipoprotein Lipase ◽  
Bovine Milk ◽  
Density Lipoprotein ◽  
High Density ◽  
Rat Adipose Tissue ◽  
Adipose Tissue Lipoprotein Lipase ◽  
Hydrolysis Of

In an incubation system in vitro with fully activated Intralipid as substrate, rat high-density lipoprotein inhibits the hydrolysis of triacylglycerol by lipoprotein lipase from rat adipose tissue, but does not inhibit hydrolysis by the enzyme from bovine milk. The pattern of inhibition suggests that substrate and high-density lipoprotein may compete for association with rat adipose-tissue lipoprotein lipase.

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