Heterogeneityof LipoproteinLp(a) and Apolipoprotein(a)

We have purified Lp(a) lipoproteinsfromsera offoursubjects by ultracentrifugation, selective precipitation, and chromato-focusing. Each subject had two forms of serum Lp(a) that were separable by chromatofocusing.We purified apolipo-protein (a) (apo(a)] from the eight isolated Lp(a)s and ob-tained only one form of apo(a) from each subject. The four apo(a)s seen on sodium dodecyl sulfate-polyacrylamide gel electrophoresishad different apparent molecular masses, ranging from 275 to 440 kDa. Chemical deglycosylationof the smallestapo(a) yielded a 235 kDa protein,which may be a core proteinstructurecommonto all apo(a)s. We conclude that there are many forms of serum Lp(a) and apo(a). The heterogeneityof serum Lp(a) particles can be ascribed in part to differencesin size of apo(a), but other factors must accountfor the existencewithina single patientof differen