The cyanogen bromide peptides of the apoprotein of low density lipoprotein (apoB): Its molecular weight from a chemical view

After >95% cleavage of the apoprotein (apoB) of the low density lipoproteins with cyanogen bromide, the peptides produced are shown to be extensively aggregated in sodium dodecyl sulfate. Both high temperature and increased concentration (5%) of the detergent are necessary to shift the aggregated peptides from high molecular weight (>25,000) to lower molecular weight aggregates as seen on sodium dodecyl sulfate polyacrylamide gel electrophoresis. End group analyses of the cyanogen bromide digestion by automated sequencer techniques indicate the presence of five (5) methionines. With a known methionine content of 16 moles/100,000 g protein, the molecular weight of the apoprotein must be approximately 30,000.