61] Purification of human fibroblast interferon prepared in the absence of serum

Abstract

Human fibroblast interferon is purified to homogeneity, and all started with interferon produced in the absence of serum. This contribution describes a recent procedure for the purification to homogeneity of large volumes of human fibroblast interferon produced in the absence of added serum. Interferon is assayed by a microtiter technique by the inhibition of vesicular stomatitis virus cytopathic effect as a measure of the interferon concentration. When this interferon is subjected to a second electrophoresis and the proteins are stained with Coomassie Blue, the data are obtained. Only one band is observed, indicating homogeneous interferon. A more vigorous proof of purity is to determine the number of peptide chains in a fraction of purified interferon. This can be done on microgram quantities of a protein by Edman degradation starting at the NH 2 terminus. More than one NH 2 -terminal amino acid sequence indicates more than one protein. The NH 2 -terminal sequence of fibroblast interferon purified by the procedure has been determined by Edman degradation. Only one sequence is found, proving that this purification procedure gives pure human fibroblast interferon.