Lipase Fluorometric Test Kit, Hepatic, BioAssay(TM)

Fluorometric tests for the analysis of triglyceride hydrolysis capacity in postheparin plasma (PHP)\nand tissue culture fluids/ cell extracts.\n\nTwo lipases are involved in the catabolism of triglyceriderich lipoproteins: lipoprotein lipase (LPL; EC 3.1.1.34) located on glucosaminoglycan chains, anchored to the luminal surface of the capillary epithelium in adipose tissue, heart and skeletal muscle; hepatic lipase (HL; EC3.1.1.3) which is almost exclusive to the endothelial cells of the liver. Both lipases are triglyceride lipases [1]. LPL is a multifunctional protein with a central role in homeostasis and a rate-limiting enzyme for the metabolism of triglyceride-rich chylomicrons and VLDL. Triglycerides of chylomicrons and very low density lipoprotein (VLDL) are the preferred substrates of LPL. An inherited deficiency ofLPL causes defective chylomicron metabolism [1]. Patients with autosomal recessive LPL defects show the symptoms of chylomicronemia and type I hyperlipidemia [2]. Heterozygote LPL deficiency has been identified as a defect of some cases of familial combined hyperlipidemia, one of the most common causes of genetic hyperlipidemia [3]. Many metabolic disorders such as diabetes, obesity, insulin resistence, hyperinsulinemia, hypothyroidism, gestational hyperlipidemia, and renal disease as well as alcohol ingestion are associated with elevated plasma triglycerides. The lipid abnormalities in these diseases can be explained as modulated or changed by LPL activity [4,5]. HL hydrolyses the triglycerides of intermediate density lipoprotein (IDL) and high density lipoprotein-2 (HDL2) [6-9]. It was further shown that the hepatic removal of chylomicron remnants is primarily mediated by mechanisms involving HL (and apolipoprotein E). After the chylomicron remnant particles have bound to the hepatocyte surface, endocytosis\nispredominantly mediated by the hepatic LDL receptor and at a slower rate by the LDL receptor-related protein (LRP) which is regulated by the receptor-associated protein (RAP) [10]. LPL and HL have been shown to bind directly to LRP [11]. HL and LPL should, therefore, be an important determinant of lipoprotein receptor pathways [12]. Retention of lipoproteins by the extracellular matrix may be another process modulated by the lipases [13]. As the affinity of lipases for heparin is higher than the heparin- sulfate-like anchor, injection of an intravenous heparin bolus displaces both enzymes into postheparin plasma (PHP), where their activity can be quantified. The Total Lipase Test can also be used to determine the activity of bacterial lipases (data available for Pseudomonas lipase).

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SPECIFICATIONS

Catalog Number

L2496-17

Size

24Tests

Applications

IF

References

1. Olivecrona T, Bengtsson-Olivecrona G (1990) Lipoprotein Lipase and Hepatic Lipase. Curr Opin Lipidol 1:222-30. 2. Zandonella G, Haalck L, Spener F, Faber K, Paltauf F, Hermetter A (1995) Eur J. Biochem 231:50-55. 3. Duque M, Graupner M, St