Johnson B J, Thames K E
J Pharm Sci. 1977 Mar;66(3):427-8. doi: 10.1002/jps.2600660330.
A number of chemical modifications were made to purified human IgG1. The effects of these modifications on the complement activity of the immunoglobulin were studied using aggregation on latex and measuring the consumption of the complement by CH50-quantitation. Tryptophan and tyrosine are implicated in the complement fixing site of this human immunoglobulin, and an arginine moiety probably provides a binding site for the complement.