| 1. |
- Olivecrona, T, et al.
(författare)
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New aspects on heparin and lipoprotein metabolism.
- 1993
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Ingår i: Haemostasis. - 0301-0147 .- 1423-0038. ; 23 Suppl 1, s. 150-60
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Tidskriftsartikel (refereegranskat)abstract
- Lipoprotein lipase (LPL) and hepatic lipase (HL) are two enzymes which participate in metabolism of plasma lipoproteins. The enzymes are located at vascular surfaces and are released from their binding sites on injection of heparin. In this paper we give a short overview of the structure of the lipases and their role in lipoprotein metabolism. Earlier studies had shown that low molecular weight (LMW) heparin preparations result in lower LPL activities in blood than do corresponding amounts of conventional heparin. Studies with organ perfusion in rats show that the two types of heparin have similar ability to release the lipases from their binding sites in extrahepatic tissues, but that LMW heparin is less effective than conventional heparin in preventing rapid uptake and degradation of LPL by the liver. After injection of heparin the metabolism of triglyceride-rich lipoproteins is initially accelerated, presumably as a result of the high levels of circulating LPL. Then follows a phase when lipoprotein metabolism is slower than normal, perhaps because endothelial LPL has been depleted by accelerated transport to and degradation in the liver.
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| 2. |
- Hultin, M, et al.
(författare)
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Release of lipoprotein lipase to plasma by triacylglycerol emulsions. Comparison to the effect of heparin.
- 1992
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Ingår i: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1125:1, s. 97-103
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Tidskriftsartikel (refereegranskat)abstract
- It was previously known that lipoprotein lipase (LPL) activity in plasma rises after infusion of a fat emulsion. To explore the mechanism we have compared the release of LPL by emulsion to that by heparin. After bolus injections of a fat emulsion (Intralipid) to rats, plasma LPL activity gradually rose 5-fold to a maximum at 6-8 min. During the same time the concentration of injected triacylglycerols (TG) decreased by about half. Hence, the time-course for plasma LPL activity was quite different from that for plasma TG. The disappearance of injected 125I-labelled bovine LPL from circulation was retarded by emulsion. This effect was more marked 30 min than 3 min after injection of the emulsion. The data indicate that the release of LPL into plasma is not solely due to binding of the lipase to the emulsion particles as such, but involves metabolism of the particles. Emulsion increased the fraction of labelled LPL found in adipose tissue, heart and the red muscle studied, but had no significant effect on the fraction found in liver. The effects of emulsion were quite different from those of heparin, which caused an immediate release of the lipase to plasma, decreased uptake of LPL in most extrahepatic tissues by 60-95%, and increased the fraction taken up in the liver.
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| 3. |
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| 4. |
- Lycksell, P O, et al.
(författare)
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Sequence specific 1H-NMR assignments and secondary structure of a carboxy-terminal functional fragment of apolipoprotein CII.
- 1992
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Ingår i: European Journal of Biochemistry. - 0014-2956 .- 1432-1033. ; 205:1
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Tidskriftsartikel (refereegranskat)abstract
- The structural properties of a synthetic fragment of human apolipoprotein CII (apoCII) has been studied by circular dichroism and proton nuclear magnetic resonance. The fragment corresponds to the carboxy-terminal 30 amino acid residues and retains the ability of apoCII to activate lipoprotein lipase. Like native apoCII, the fragment has a tendency to self-associate in pure aqueous solution. Addition of 1,1,1,3,3,3-hexafluoro-2-isopropanol to aqueous solvent dissolves the aggregates and leads to an increase in the alpha-helical content of the peptide, probably by stabilizing transient helical structures. The resonances in the 1H-NMR spectrum of the fragment in 35% (CF3)2CHOH were assigned through standard procedures from nuclear Overhauser enhancement spectroscopy, correlated spectroscopy and total correlated spectroscopy experiments. The NMR data indicates the formation of a stable alpha helix spanning Ile66-Gly77. Another alpha helical turn may be formed between Lys55 and Ala59 and possibly span even further towards the carboxyl terminus. These structural elements are different from those previously predicted for this part of the sequence of apoCII.
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