Biosynthesis of Ovalbumin

Abstract

THE problem of the biosynthesis of ovalbumin is interesting since this protein seems to be synthesized from a non-homogeneous pool of intermediary peptides^1–3. We have studied the biosynthesis of this protein in vivo by the laying hen using L-cystine-³⁵S and Na₂ ¹⁴CO₃. Selected birds were given these labelled substances and blood was obtained at stated intervals, either by heart puncture or from the wing vein. The time of laying the egg was carefully noted and ovalbumin was isolated from the egg white by ammonium sulphate fractionation. Serum globulin was isolated by precipitation with an equal volume of ammonium sulphate, while the total proteins were obtained by precipitation with trichloracetic acid to a final concentration of 5 per cent. In both cases the precipitates were repeatedly washed with 5 per cent trichloracetic acid to remove any co-precipitated amino-acids.