Interactions of C-reactive protein with the first component of human complement.
Explore the source record for details and available documents.
Binding Sites↗
Biomedical subjects
D R Claus
Publications and source records attributed to D R Claus.
Complement activation by interaction of polyanions and polycations. III. Complement activation by interaction of multiple polyanious and polycations is the presence of C-reactive protein.
Interactions between heparin and protamine previously were found to result in activation of the complement (C) system. In the present investigation, this interaction was shown to result in the binding of purified C1, and this was markedly enhanced in the presence of C-reactive protein (CRP). CRP also enhanced C consumption during heparin-protamine interactions in whole serum, and in the presence of CRP depletion of C components C1-3 was observed. Similar C1 binding and C consumption in the presence of CRP were seen upon the interaction of multiple additional polyanions including DNA, ENA, hyaluronic acid, chondroitin sulfate, and dextran sulfate with the polycations protamine sulfate and poly-L-lysine. These effects were observed with CRP concentrations well within the range found in normal human sera and considerably less than those found in most acute phase sera. We suggest, therefore, C activation by polyanion-polycation interactions in the presence of CRP may be important to certain reactions of host defense and inflammation.
Anions↗
Radioimmunoassay of human C-reactive protein and levels in normal sera.
C-reactive protein (CRP) has been considered an acute-phase protein which appears only during reactions of tissue injury or inflammation. We report here the quantitation of CRP levels in normal adults and neonates made possible by the development of a sensitive and precise radioimmunoassay for human CRP which enables the detection of 3 ng. per milliliter. Serum levels in 153 healthy blood donors ranged from 68 to 8,200 ng. per milliliter, with a median value of 580 ng. per milliliter (mean = 1,340 ng. per milliliter). CRP levels in 24 normal cord serum samples ranged from 10 to 370 ng. per milliliter, with a median value of 70 ng. per milliliter (mean = 109 ng. per milliliter). CRP levels in 246 individuals evaluated for autoimmune diseases ranged to 256,000 ng. per milliliter with a median value of 13,000 ng. per milliliter (mean = 38,000 ng. per milliliter). No individual lacking CRP was detected. Thus, CRP can be considered a component of normal serum which only increases dramatically in concentration during inflammation.
Adult↗
Multiplicity of leucine transport systems in Escherichia coli K-12.
The major component of leucine uptake in Escherichia coli K-12 is a common system for l-leucine, l-isoleucine, and l-valine (LIV-I) with a Michaelis constant (K(m)) value of 0.2 muM (LIV-I system). The LIV-binding protein appears to be associated with this system. It now appears that the LIV-I transport system and LIV-binding protein also serve for the entry of l-alanine, l-threonine, and possibly l-serine. A minor component of l-leucine entry occurs by a leucine-specific system (L-system) for which a specific leucine-binding protein has been isolated. A mutant has been obtained that shows increased levels of the LIV-I transport activity and increased levels of both of the binding proteins. Another mutant has been isolated that shows only a major increase in the levels of the leucine-specific transport system and the leucine-specific binding protein. A third binding protein that binds all three branched-chain amino acids but binds isoleucine preferentially has been identified. The relationship of the binding proteins to each other and to transport activity is discussed. A second general transport system (LIV-II system) with a K(m) value of 2 muM and a relatively low V(max) can be observed in E. coli. The LIV-II system is not sensitive to osmotic shock treatment nor to growth of cells in the presence of leucine. This high K(m) system, which is specific for the branched-chain amino acids, can be observed in membrane vesicle preparations.
Alanine↗