Summary
Mg++ is required for the inactivation of C′3 by insoluble residues of yeast cells (zymosan). The concentration of Mg++ in normal serum is more than adequate for the reaction to proceed optimally. The requirement for Mg++ is also demonstrated by the greater uptake of serum nitrogen by zymosan in the presence of Mg++ than in its absence.
The inactivation of human C′3 by zymosan appears to be a stoichiometric reaction sharply dependent on temperature, ionic strength and pH. The optimum conditions are at 37 C, ionic strength 0.15 or less, and pH 6.8–8.6.
The complex formed upon the addition of zymosan to serum is highly undissociable or results in the destruction of C′3 activity. Attempts to elute C′3 from the zymosan complex were unsuccessful.
Footnotes
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↵1 This investigation was supported in part by a grant from Lederle Laboratories Division, American Cyanamid Company, and in part by a grant from the National Institutes of Health, Public Health Service.
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↵2 In view of the results to be presented, it is recognized that use of the expression “inactivation of C′3 by zymosan” may be misleading. Nevertheless, for brevity and convenience, it will be employed to indicate the loss of C′3 activity upon the addition of zymosan to serum.
- Received June 22, 1953.
- Copyright © 1953 by The American Association of Immunologists, Inc.
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