Physiocochemical properties of a lipoprotein antigen of Echinococcus granulosus.

Molecular weight and optical properties of the lipoprotein B, the main antigen produced by the parasite in sheep hydatid fluid, have been determined. By sedimentation equilibrium studies, its molecular weight has been found equal to 120,000. Circular dichroism and optical rotatory dispersion spectra are consistent with an alpha-helix content of about 50%, and this ordered structure is not completely destroyed by dissociation in guanidinium choloride. The ORD spectrum is discussed in relation to the biological function of the lipoprotein antigen.