Key result
Apoprotein-depleted chylomicrons had a 90% and 75% decreased capacity to act as a substrate for lipoprotein lipase in vitro and in situ, respectively, compared with intact chylomicrons.
Why the study?
Does apoprotein depletion of chylomicrons decrease their capacity to act as a substrate for lipoprotein lipase?
Does apoprotein depletion of chylomicrons decrease their capacity to act as a substrate for lipoprotein lipase?
Apoproteins are essential for the catabolism of triacylglycerol-rich lipoproteins by lipoprotein lipase, as demonstrated by the reversible loss of substrate capacity in trypsin-treated chylomicrons.
Answers are grounded in this paper and cite their sources.
Apoprotein dependence of chylomicron lipolysis may extend to human triglyceride metabolism; leaves open relevance for clinical lipoprotein disorders.
Rat lymph chylomicrons were exposed to soluble and to immobilized trypsin. This treatment caused no detectable changes in the chylomicron structure or lipid composition, but did result in virtually total depletion of all their tetramethylurea-soluble apoproteins. 2. The capacity of these apoprotein-depleted chylomicrons to act as substrate for lipoprotein lipase in vitro and in situ (i.e. isolated perfused rat heart) was decreased by about 90 and 75% respectively, compared with intact chylomicrons. 3. On incubation with rat plasma high-density lipoproteins, trypsin-treated chylomicrons readily acquired a full apoprotein complement. This resulted in the complete restoration of their capacity to act as substrate for lipoprotein lipase both in vitro and in situ. 4. It is suggested that with the use of try,sin-treated chylomicrons it is now possible for the first time to investigate the physiological role that individual apoproteins play in the catabolism of triacylglycerol-rich lipoproteins by lipoprotein lipase.
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Lukens et al. (1978) studied this question. Trypsin treatment (apoprotein depletion) vs. Intact chylomicrons was evaluated on Capacity to act as substrate for lipoprotein lipase in vitro and in situ. Apoprotein-depleted chylomicrons had a 90% and 75% decreased capacity to act as a substrate for lipoprotein lipase in vitro and in situ, respectively, compared with intact chylomicrons.
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