Physical Properties of Chick Interferon

Abstract

The sedimentation coefficient, diffusion coefficient, and molecular weight of chick-embryo interferon were determined by zone centrifugation and equilibrium sedimentation in caseium chloride density gradients, and by chromato-graphy on Sephadex G-100 columns. Purified interferon is not available in quantities sufficient to permit direct analysis by chemical or physical means; its relative concentrations were determined, therefore, by bioassay. I125-human serum albumin was used as an internal reference in all experiments. The sedimentation coefficient of chick-embryo interferon is 2.2 to 2.3S; the diffusion coefficient is 9.5 X 10-7 cm2 sec-1. A molecular weight of 26,000 was calculated from the sedimentation and diffusion coefficients, and a range of 25,000 to 34,000 daltons was obtained from equilibrium-sedimentatmon analyses.