X-Ray Crystallographic Measurements on a Single Crystal of a Tobacco Necrosis Virus Derivative

Abstract

IN August 1944, N. W. Pirie, of Rothamsted, sent us a few large crystals of a tobacco necrosis virus derivative (Rothamsted strain)¹ on which we have been able to make some X-ray measurements. Before we could complete the investigation the preparation unfortunately deteriorated, but the crystals are in themselves so remarkable that it seems worth while to give a preliminary account of their characteristics. They are described as of a crystalline derivative rather than as crystals of the virus itself, since by the time the preparation had crystallized it had lost its infectivity. It shows, however, the same serological and ultracentrifugal behaviour as the active material and so probably does not differ greatly from this². The molecular weight indicated by the sedimentation constant is at least 1,850,000, and this order of magnitude is confirmed by our present measurements.