Lipoproteins are a class of spherical particles consisting of a hydrophobic core rich in sterolipids and triglycerides and a shell composed of proteins, phospholipids, and cholesterol. Lipoproteins play an important role in the packaging, storage, transport and metabolism of extracellular lipids in insects and mammals. Depending on their density, size and protein composition, lipoproteins can be classified into five main categories: celiac particles (CM), very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), low density lipoproteins (LDL) (mainly apoB-containing lipoproteins), and high density lipoproteins (HDL) (mainly apoA1-containing lipoproteins).
Abnormalities in lipoprotein metabolism (usually accompanied by alterations in the lipid and protein fractions) are strongly associated with atherosclerosis, diabetes, obesity, and tumorigenesis. The lipid fractions of lipoproteins are mainly cholesterol and triglycerides from dietary intake and hepatic synthesis. Of these, cholesterol is a structural component of biological membranes and its content affects membrane stability, permeability and protein mobility, and is required for the biosynthesis of sex hormones and bile acids. Triglycerides are a source of metabolic energy. The protein fraction of lipoproteins (also often called apolipoprotein, apolipoprotein) is mainly involved in lipid transport and metabolism and has important functions such as acute phase response, complement activation, immune response, inflammatory response, and protease inhibitor.
Creative Proteomics offers a comprehensive range of services for lipoprotein analysis, including lipoprotein fractionation, lipoprotein sample purification, and mass spectrometry-based lipoprotein analysis techniques.
Lipoprotein fractionation is a crucial step in isolating and characterizing different lipoprotein subclasses. Creative Proteomics employs advanced fractionation techniques, including ultracentrifugation, size-exclusion chromatography, and density gradient ultracentrifugation, to separate lipoprotein particles based on their size and density. This fractionation process allows for detailed analysis of individual lipoprotein subclasses and their distinct properties.
Creative Proteomics provides comprehensive lipoprotein sample purification services to obtain high-quality lipoprotein samples for downstream analysis. Through a combination of ultracentrifugation, selective precipitation, and affinity chromatography, lipoprotein samples are purified from complex biological matrices, ensuring accurate and reliable results. The purified lipoprotein samples can then be utilized for further characterization and analysis.
At Creative Proteomics, we prioritize accurate quantification of lipoproteins. To achieve this, we utilize the external standard method for quantification and employ internal standards for correction. This approach enhances the accuracy of both qualitative and quantitative analyses, ensuring reliable and precise results.
Gel permeation high-performance liquid chromatography (HPLC) is a powerful technique employed by Creative Proteomics for lipoprotein analysis. This method separates lipoproteins based on their hydrated particle size using size exclusion chromatography (SEC) principles. By passing the lipoprotein samples through a porous stationary phase, larger lipoprotein particles are eluted earlier, while smaller particles are eluted later. This separation technique enables the characterization and quantification of lipoprotein subclasses, contributing to a deeper understanding of lipoprotein biology.
Creative Proteomics utilizes liquid chromatography-tandem mass spectrometry (LC-MS/MS) for lipoprotein analysis. This technique combines the separation capabilities of liquid chromatography with the exceptional sensitivity and specificity of triple quadrupole mass spectrometers. Our state-of-the-art platform, the Triple Quad™ 6500 LC-MS/MS System, enables precise and reliable analysis of lipoproteins. This platform facilitates the identification and quantification of lipoprotein components, such as lipids and apolipoproteins, providing comprehensive insights into lipoprotein composition and function.
Fig 1. The workflow of lipoproteinss analysis service.
Creative Proteomics also employs matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for lipoprotein analysis. This technique is particularly useful for determining the molecular mass of intact proteins present in lipoproteins. By ionizing the intact protein molecules with a laser, MALDI-TOF-MS allows for accurate measurement of their mass, providing valuable information about the protein composition and structure within lipoprotein particles.
For the measurement of key lipoprotein biomarkers, particularly triglycerides (TG) and total cholesterol (TC), Creative Proteomics employs the isotope-dilution mass spectrometry (ID/MS) technique. This powerful method offers high sensitivity and accuracy by utilizing isotopically labeled internal standards for precise quantification. Additionally, the quantification of apolipoproteins is achieved through liquid chromatography ID/MS (LC-ID/MS), enabling comprehensive characterization of lipoprotein composition.
|Chylomicrons||Very-low-density lipoproteins (VLDL)||Intermediate-density lipoproteins (IDL)||Low-density lipoproteins (LDL)||High-density lipoproteins (HDL)|
|Lipoprotein(a) [Lp(a)]||Pre-beta-HDL||Pre-beta-VLDL||Remnant lipoproteins||Very large HDL|
|Small dense LDL||Oxidized lipoprotein(a) [oxLp(a)]||Oxidized low-density lipoprotein (ox-LDL)||Lipoprotein complexes (LDL-IC)||Large buoyant LDL (lbLDL)|
|High-density lipoprotein cholesterol (HDL-C)||Very low-density lipoprotein (VLDL)||Cholesteryl ester transfer protein (CETP)|
Sample Types: We accept various sample types for lipoprotein analysis, including:
Sample Volume: The recommended sample volume may vary depending on the specific analysis and services requested. However, to ensure reliable results, it is advisable to provide an adequate sample volume. Here are the general guidelines:
Cardiovascular Disease Research
Cardiovascular diseases, including atherosclerosis and coronary artery disease, are major causes of morbidity and mortality worldwide. Lipoproteins, particularly LDL and HDL, play pivotal roles in the development and progression of these diseases. By analyzing the composition, size, and functionality of lipoproteins, researchers can unravel the underlying mechanisms and identify potential biomarkers for cardiovascular diseases. Lipoprotein analysis provides critical insights into lipoprotein metabolism, cholesterol transport, and their association with plaque formation.
Metabolic disorders, such as obesity, diabetes, and metabolic syndrome, are characterized by dysregulation in lipid metabolism. Lipoprotein analysis enables researchers to examine the alterations in lipoprotein profiles, including changes in lipoprotein particle size, density, and apolipoprotein composition. Understanding these alterations helps in elucidating the relationship between lipoproteins and metabolic disorders, paving the way for potential therapeutic interventions.
Lipids are essential components of cellular membranes, serving structural and functional roles in various biological processes. Lipoprotein analysis provides researchers with a comprehensive understanding of lipid metabolism, distribution, and transport. By studying the composition and properties of lipoproteins, scientists can unravel the intricate mechanisms involved in lipid homeostasis, lipid signaling, and lipid-related disorders.