In vitro Catabolism of very low density lipoproteins from horse (Equus caballus) by the action of autologous lipoprotein lipase.

The research explores how the enzyme lipoprotein lipase, when isolated from horse plasma, affects the density and composition of very low-density lipoproteins. It was found that after incubation, the lipoproteins increased in density and underwent a change in their fatty acid composition, with a significant reduction in linolenic acid content.

Methodology

• The primary approach relied on the in vitro incubation of very low-density lipoproteins (VLDL) sourced from horses.
• The VLDLs were combined with lipoprotein lipase, an enzyme isolated from post-heparin horse plasma, an effective enzyme known to increase the density of these lipoproteins.

Findings

• Following the incubation period, the lipoproteins increased in density, turning into low-density lipoproteins (LDL).
• The biochemical composition of these lipoproteins underwent significant changes. The LDLs derived from the in vitro process had a radically different chemical makeup compared to the original VLDLs and plasma lipoproteins.
• Specifically, in vitro-derived LDLs had a substantially higher content of phospholipids and triacylglycerols (types of fats) compared to their native counterparts.
• Contrarily, they had a significantly lower amount of cholesteryl esters, which are forms of cholesterol.

Analysis of Fatty Acid Composition

• The researchers also compared the patterns of fatty acid in the triacylglycerol component of the plasma VLDLs and the in vitro-obtained LDLs.
• They found a drastic decrease in the proportion of linolenic acid, an essential fatty acid, as the lipoprotein density increased.

Implications

• This research suggests that the enzyme lipoprotein lipase alters the density and composition lipoproteins.
• These findings could have implications for understanding metabolic processes and disorders related to lipoprotein metabolism in horses, and potentially in other species.