Apolipoprotein B (ApoB) is the indispensable structural backbone of every atherogenic lipoprotein particle in human plasma — one ApoB-100 molecule per LDL, VLDL, IDL and Lp(a) particle. YO Proteins cat. 650 is native, full-length human ApoB-100 isolated from pooled healthy donor plasma under non-denaturing conditions that preserve the receptor-binding conformation. The preparation is supplied as a 0.5 mg lyophilised vial — freeze-dried from a 50 mM Na2CO3 (pH 10) / 50 mM NaCl / deoxycholate solution that keeps the highly hydrophobic ApoB-100 monomer soluble through the freeze-drying step — intended for use as an immunoassay antigen and standard, a Western-blot reference, and a binding partner in receptor / lipoprotein-particle studies.
ApoB-100 is a 4 563-residue, ~515 kDa monomeric protein synthesised in the liver where it is required for the assembly and secretion of very-low-density lipoprotein. After lipolytic remodelling in the circulation, ApoB-100 remains the single, non-exchangeable apolipoprotein of LDL, where it acts as the high-affinity ligand for the LDL receptor and directs the hepatic clearance of cholesterol-rich particles. The intestinal isoform ApoB-48 corresponds to the N-terminal 48 % of ApoB-100 and assembles chylomicrons after dietary fat absorption.
Because ApoB stoichiometry is one molecule per particle, plasma ApoB concentration is a direct count of circulating atherogenic particles — an emerging gold-standard cardiovascular risk marker that outperforms LDL cholesterol in statin-treated and discordance populations. Native, full-length ApoB-100 reference material is essential for calibrating ELISA and turbidimetric assays, generating peptide-derived antigen panels (the p45 and p210 epitopes are widely used in cardiovascular autoimmunity research), and reconstituting LDL-like particles in vitro.
SPECIFICATIONS
Catalogue number: 650
Product name: Apolipoprotein B (human)
Source: Pooled healthy human donor plasma
Isoform: ApoB-100 (the full-length 4 563-residue hepatic isoform)
Molecular weight: ~515 kDa (monomer)
Gene symbol: APOB (aliases FLDB, LDLCQ4; protein aliases apo B-100, apoB-100, apoB-48, apolipoprotein B-100, apolipoprotein B48)
UniProt: P04114
Purity: =95 % (SDS-PAGE)
Format: Lyophilised from a non-sterile solution containing 50 mM Na2CO3 (pH 10), 50 mM NaCl, and deoxycholate
Package size: 0.5 mg
Grade: Research use only (not for diagnostic or therapeutic use)
STORAGE / RECONSTITUTION
Supplied as a lyophilised powder. The lyophilisation buffer contains 50 mM Na2CO3 (pH 10), 50 mM NaCl, and deoxycholate — included to keep ApoB-100 soluble during freeze-drying. Reconstitute in sterile water or in the user's working buffer at the desired protein concentration; brief gentle pipetting is sufficient — do not vortex. Centrifuge briefly to collect material at the bottom of the vial before opening.
The reconstituted material carries over deoxycholate from the lyophilisation buffer. For applications sensitive to detergent (cell-based assays, certain receptor-binding measurements), dialyse against the user's working buffer or perform a buffer-exchange step (Zeba / Amicon) before assay. For ELISA coating, dilute the reconstituted protein to 1–10 µg/mL in carbonate / bicarbonate coating buffer (pH 9.6) immediately before use — the high-pH carbonate of the supplied buffer is already compatible with standard alkaline coating protocols. For Western-blot positive-control loading, use 50–200 ng / lane under reducing conditions.
Because the lyophilisate is supplied non-sterile, it is intended for in-vitro research use. Filter-sterilise the reconstituted solution (0.22 µm) before use in cell culture. Avoid repeated freeze–thaw of the reconstituted aliquots; prepare single-use aliquots immediately after reconstitution.
Store the lyophilised vial at -20 °C. After reconstitution, prepare single-use aliquots and store at -20 °C; working aliquots may be held at +2–8 °C for up to one week. Avoid repeated freeze–thaw cycles, which can compromise the receptor-binding conformation and reduce immunoassay sensitivity.
APPLICATIONS
- ELISA antigen / coating protein for the detection and quantification of anti-ApoB autoantibodies (IgG and IgM) in human serum
- ELISA standard / reference protein for absolute quantification of plasma ApoB
- Western-blot positive control and migration marker for ApoB-100 (~515 kDa) and proteolytic / oxidative fragments
- Immobilised ligand for LDL-receptor (LDLR) and LRP1 binding assays — surface plasmon resonance, microscale thermophoresis, BLI
- Substrate / starting material for the generation of malondialdehyde- and copper-oxidised ApoB epitopes used in cardiovascular autoimmunity studies (oxLDL / MDA-LDL surrogate antigens)
- Reference antigen for generation and epitope-mapping of monoclonal and polyclonal anti-ApoB antibodies
- Component for in-vitro reconstitution of LDL-like nanoparticles for drug-delivery and lipoprotein-tracer research
- Antigen panel building for cardiometabolic-risk biomarker discovery (anti-ApoB IgG / IgM peptide arrays, p45 / p210 epitope-derived panels)
- Hepatocyte-secretion and lipoprotein-assembly studies — Western blot detection of cell-secreted ApoB into culture supernatants
- Immunisation antigen for custom polyclonal antibody production
APPLICATION HIGHLIGHTS — HIGH-VALUE RESEARCH NICHES
- Native, full-length ApoB-100 calibrator and coating antigen for ApoB Enzyme-Linked Immunosorbent Assay, immunoturbidimetry and lateral-flow assay development.
- Immunogen and specificity control for anti-human ApoB antibody generation and epitope mapping.
- Substrate for LDL-receptor and LDL-receptor-related protein binding studies, and for PCSK9 pathway research.
- Reference material for oxidised-LDL / malondialdehyde-ApoB adduct chemistry in atherosclerosis research.
- Positive control for Western blot and mass-spectrometry-based apolipoprotein quantification workflows.
- Antigen for autoantibody (anti-oxLDL / anti-ApoB) profiling in cardiovascular and autoimmune studies.
REFERENCES
1. Engelbertsen D, Rattik S, Knutsson A, Björkbacka H, Bengtsson E, Nilsson J. Induction of T helper 2 responses against human apolipoprotein B100 does not affect atherosclerosis in ApoE-/- mice. Cardiovasc Res. 2014 Jul 15;103(2):304-12. doi: 10.1093/cvr/cvu131. Epub 2014 May 27. PubMed PMID: 24866382
