Isolation of glucosamine from the capsids of a picornavirus.

The purified capsids of echovirus I2 were found to contain radioactivity when radioactive glucosamine was provided for virus-infected cultures. Radioactivity was identified with glucosamine, after recovery from the virus particles by acid hydrolysis and paper chromatography. Although the label was not removable from the isolated virus particles without destruction of virus, polyacrylamide gel electrophoresis showed that it was not covalently bound to any of the four virus polypeptides since it migrated more rapidly and was identical electrophoretically to the glucosamine-labelled fraction isolated from uninfected cells. Glucosamine labelling of virus capsids was only achieved during virus multiplication, since labelled fractions from uninfected cells did not bind to virus capsids. Its apparently low tool. wt., lack of associated virus or cellular proteins, lack of labelling of virus with other radioactive sugars, and the similar electrophoretic migration of free N-acetyl glucosamine suggested that the component is an acetylated product that is trapped during the assembly of the virus.