Diffusion of Proteins through a Wedge-shaped Agar Gel

Abstract

A WEDGE-SHAPED agar gel is formed by pouring out 10 ml. of a hot 2 per cent agar solution (‘Bacto-Agar’, Difco Laboratories) on a pre-warmed glass plate (16 cm. × 4 cm.), which is slightly inclined. After cooling down, the agar sets to a wedge-shaped gel, which measures 2.5 mm. at the thick end and 0.2 mm. at the thin end. It can easily be detached from the glass plate with a spatula. In the meantime another agar gel is formed, using the technique we have described for immune-electrophoresis¹ ; 10 ml. of a hot 1.5 per cent agar solution are poured on a hot glass plate, as they are used in the ‘Elphor’ paper strip scanner. The agar gel, setting on the exactly horizontal glass plate, has a thickness of 1.5 mm. Now the wedge-shaped agar gel is laid upon it ; this is done slowly so that no air remains between the two agar gels. Paper strips, 2 mm. broad, of Swedish ‘Munktell’ 20/150 paper are soaked in 2 per cent solutions of serum albumin (human), γ-globulin (Central Laboratory of the Swiss Red Cross, Berne) and α₂-macroglobulin (Behringwerke, Marburg/Lahn) in 0.86 per cent sodium chloride. These paper strips are laid parallel upon the wedge-shaped agar gel. After 24 hr. in a wet chamber they are removed and the agar wedge is placed on a glass plate. Both agar gels are now bathed in a 2 per cent solution of acetic acid for 2 hr. then they are dried under infra-red light and stained with amido-black.