Determination of the molecular mass of apolipoprotein B-100 A chemical approach

Abstract

Apolipoprotein B-100 (apo B-100) is the protein ligand in low-density lipoproteins that binds to a specific cell-surface receptor. Its molecular mass has been a subject of controversy. We have determined the molecular mass of the protein by a chemical approach. After complete CNBr cleavage, the C-terminal fragment of apo B-100 was purified by reverse-phase h.p.l.c. Amino acid N- and C-terminal analyses confirm that this peptide represents the C-terminal peptide as deduced from the DNA sequence of a human apo B-100 cDNA clone. A chemically synthesized peptide was used to determine the recovery of the peptide (74.72%). On the basis of these data, the molecular mass of apo B-100 was determined to be 496.82 +/- 24.84 kDa.

Quantifying apolipoprotein(a) in the era of proteoforms and precision medicine

“…ApoB contains 19 potential N-glycosylation sites, of which 17 have previously been reported to be occupied by high-mannose, complex and hybrid type N-glycans [47,48]. Specifically, the glycosylation on apoB was determined to be approximately 4-10% of its total weight [49], with the most abundant glycans being the monosialylated biantennary glycans (29.2%), bisialylated biantennary glycans (23.6%), nonsialyated biantennary glycans (7.2%), and high mannose glycans (> 15.5%) [47]. Interestingly, glycosylation patterns of apoB were reported to be rather consistent between normolipidemic, hypertriglyceridemic and hypercholesterolemic individuals [47], but true biological variation data on apoB glycosylation are, similar to apo(a), lacking.…”

Steric contribution of macromolecular crowding to the time and activation energy for preprotein translocation across the endoplasmic reticulum membrane

“…Average-sized proteins have masses on the order of 50 kDa and several hundred amino acids; Ero1p is an example with a mass of 65 kDa and N = 560 aa [36,37]. Finally, there are a few large proteins with masses on the order of several hundred kDa and several thousand amino acids; ApoB is one example with mass ≈500 kDa and N = 4536 aa [38][39][40][41]. Considering these data, we set the following range:…”

Apolipoproteins and metabolism in atherosclerosis

“…Yang, et al, (8) had proposed a model for apo B-100 on the surface of LDL which differs from the classical one (Figure 1). In their model, apo B exists as an extended structure so that portions of the apo B are on the surface while other portions are buried.…”