The isolation, characterisation and quantification of the equine plasma lipoproteins.

This study investigates the isolation, characterisation, and quantification of blood plasma lipoproteins in Thoroughbred horses and Shetland ponies. It highlights the particle size, lipid formation, and overall composition of these lipoproteins, showing that high-density lipoprotein (HDL) is the most dominant in horses, making up 61% of the total plasma lipoprotein mass.

Methodology and Isolation

In the research, the scientists used gel filtration chromatography and rate-zonal ultracentrifugation to isolate plasma lipoproteins from the blood of eight Thoroughbred horses and eight Shetland ponies. These techniques were deployed according to particle size and density.

• Gel filtration chromatography is a method used to separate particles based on their size.
• Rate-zonal ultracentrifugation is an approach used to separate particles according to their density.

Characterisation of Lipoproteins

Three main classes of lipoproteins – very low-density lipoproteins (VLDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL) were identified in the research. Each lipoprotein’s characteristics were defined by their lipid and apolipoprotein structures. Below are specific features found for each class of lipoprotein:

• VLDL: Found in a single population of particles, it was rich in triglyceride (a type of fat found in the blood) but had low levels of cholesterol, phospholipid, and protein.
• LDL: Characterised by high cholesterol richness. It was found to have diverse subfractions based upon particle size and lipid composition.
• HDL: Found to be composed of homogeneous particles, primarily rich in protein. HDL was found be the most common among the three, accounting for 61 percent of total plasma lipoprotein mass.

Protein Identification Using Apolipoprotein

Apolipoprotein (apo), a protein that binds lipids to form lipoproteins, was used to identify two primary proteins in VLDL and LDL, with molecular weights matching those of human apoB-100 and apoB-48. ApoA-I was the predominant protein in the equine HDL.

Breed Differences and Lipid Composition

The study observed no significant differences in the physical or chemical properties of each lipoprotein class between Shetland ponies and Thoroughbred horses. However, the Shetland ponies tended to have higher plasma triglyceride and VLDL concentrations compared to their Thoroughbred counterparts.