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Updated: Jun 19, 2026
08:26
Measuring the 50% Haemolytic Complement (CH50) Activity of Serum
Published on: March 29, 2010
THE THERMOLABILITY OF COMPLEMENT, IN RELATION TO THE HYDROGEN ION CONCENTRATION
1Hoagland Laboratory, Brooklyn.
The Journal of General Physiology
|October 30, 2009
Summary
Complement stability is highest at pH 6.1-6.4, likely its isoelectric point. Sodium chloride protects complement from heat inactivation on the alkaline side of this pH.
Area of Science:
- Immunology
- Biochemistry
Background:
- Complement is crucial for immune responses.
- Understanding complement's thermal stability is vital for its use in diagnostics and therapeutics.
Purpose of the Study:
- To determine the optimal pH for complement stability during heating.
- To investigate the role of ions and protein fractions in complement thermoinactivation.
Main Methods:
- Heating complement in diluted distilled water across a range of pH values.
- Assessing complement activity and preservation of function.
- Analyzing the influence of sodium chloride (NaCl) and protein fractions.
Main Results:
- Complement destruction was minimal at pH 6.1-6.4, corresponding to the isoelectric point of a euglobulin compound.
- Thermoinactivation involved reactions between euglobulin ions and pseudoglobulin/albumin fractions.
- NaCl protected complement from heat on the alkaline side of pH 6.1-6.4 by reducing euglobulin ionization.
Conclusions:
- The optimal pH for complement stability is 6.1-6.4.
- Complement thermoinactivation is a complex process involving interactions between different serum protein fractions.
- Ionic conditions, particularly the presence of NaCl, significantly influence complement's heat sensitivity.
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