Biophysical and Biochemical Heterogeneity of Purified Hepatitis B Antigen

Abstract

Hepatitis B antigen of the D (a+, d+, y−) subtype was purified from plasma of apparently healthy persons and from hepatitis patients. The original samples contained 20- and 42-nm particles and tubular forms (20-nm diameter). Ultracentrifugation during the purification procedure yielded pellets which were then treated at p H 2.4. Both the large, 42-nm Dane particles and the tubular forms were lost during the acid treatment of the pelleted particles, yielding a preparation containing a mixture of particles approximately 20 and 25 nm in diameter. This difference in size was substantiated in that two distinct molecular weights were calculated from high-speed equilibrium data, 3.6 × 10 6 and 4.5 × 10 6 . Further heterogeneity was observed in that hepatitis B antigenic activity was present in purified particles with an isoelectric p H of 4.0 and also in those with a p H of 4.4. No significant differences were observed in the gross amino acid composition of purified antigen obtained from plasma of three different persons. 125 I-labeled, purified antigen was found to contain six distinct polypeptides with molecular weights ranging from 10,000 to 39,000.