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Amyloid 'degrading factor activity': a non-specific calcium-mediated effect.
Clinical Science (London, England : 1979)
|March 1, 1985
Summary
Serum contains a factor that appears to degrade amyloid fibrils. However, this "amyloid degrading factor" activity is likely a non-specific, calcium-mediated effect on protein aggregation, not true proteolytic degradation, and may lack clinical significance.
Area of Science:
- Biochemistry
- Immunology
- Pathology
Background:
- Serum's ability to clarify amyloid-containing gels was attributed to an 'amyloid degrading factor'.
- This factor was thought to degrade amyloid fibrils, particularly AA amyloid.
Purpose of the Study:
- To investigate the nature of the serum 'amyloid degrading factor'.
- To determine if this activity is specific to amyloid fibrils and its relationship to serum composition and disease states.
Main Methods:
- Agarose plate assay using AA amyloid fibrils, AL amyloid fibrils, and reticulin preparations.
- Correlation analysis with serum albumin concentration and testing of purified albumin.
- Assessment of effects of EDTA, calcium, magnesium, and enzyme inhibitors.
Main Results:
- Serum from healthy donors and rheumatoid arthritis patients exhibited 'degrading activity' against AA amyloid and reticulin, but not AL amyloid.
- This activity correlated with serum albumin concentration and was mimicked by purified albumin.
- The effect was calcium-dependent, inhibited by calcium/magnesium, and only partially affected by enzyme inhibitors, suggesting a non-specific aggregation change rather than proteolysis.
Conclusions:
- Serum 'degrading factor activity' against AA amyloid and reticulin is a non-specific, calcium-mediated effect.
- The process likely involves altered protein aggregation rather than proteolytic degradation.
- The pathophysiological significance of this in vitro phenomenon is questionable.