VITELLOGENIN IN THE EGGS OF THE COCKROACH, BLATTELLA GERMANICA: PURIFICATION AND CHARACTERIZATION

Vitellogenin in the eggs of Blattella germanica was solubilized with solutions at high salt concentrations and high pH. This protein was purified by ammonium sulfate precipitation, acetic acid precipitation, DEAE-cellulose chromatography, and hydroxylapatite chromatography, into a chromatographically homogeneous state. By sucrose density gradient centrifugation, the purified vitellogenin was resolved into two components. The relative amounts of the two components varied according to the pH of the solution. An equilibrium seemed to exist in the interconversion between them when the conditions of the solution were fixed. It is suggested that aggregation and disaggregation of the vitellogenin molecules may account for the apparent heterogeneity.