Specific alteration of Sendai virus glycoprotein subunits.

The alteration produced by chemical and physical agents in the structure and neuraminidase activity of Sendai virus glycoproteins was studied. While dissociation of glycoproteins with 1% sodium dodecyl sulphate (SDS), 2% beta-mercaptoethanol and 5 M urea for 2 min at 100 degrees C yielded the known HN and F subunits (mol. wts. 60,000 and 53,000), in the presence of 1% SDS the glycoproteins were converted into components with approximate mol. wts. of 60,000, 120, 000 and higher. Treatment of the glycoproteins with 2% beta-mercaptoethanol and 0.1% SDS favoured the formation of a single component with a mol. wt. of 75,000. The alterations in the glycoprotein structure were very likely caused by their free -SH groups content. An average value of 6 free -SH groups per glycoprotein subunit was estimated. Glycoproteins stored at 4 degrees C contained only 53,000 mol. wt. subunits. During storage a kind of conversion of 67,000 to 53,000 mol. wt. components took place, preserving about 60% of the initial neuraminidase activity.