Spontaneous activation of reconstituted and serum C1 and the role of C1-inhibitor.
Evidence will be presented that first order, spontaneous activation of solution C1 at 37 degrees C under physiological conditions is a very slow process with a half-life of the order of one day and perhaps considerably longer. In addition, negative evidence will be presented showing that the formation of functionally significant levels of a complex between C1-Inhibitor and unactivated C1 does not occur. Such a complex had been previously postulated to explain the strong inhibition of the spontaneous activation of C1 which was observed upon the addition of C1-Inhibitor. Rather, we shall demonstrate that C1 catalytically activates C1, and that a critical role for C1-inhibitor is to complex with C1 to eliminate this autocatalytic reaction.
Schumaker
V N
VN
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Tseng
Y
Y
Poon
P H
PH
Bianchino
A C
AC
Zavodszky
P
P
D002384:Catalysis; D003167:Complement Activation; D003172:Complement C1 / Q000378:metabolism*; D003174:Complement C1 Inactivator Proteins / Q000502:physiology*; D003171:Complement Pathway, Classical; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D011485:Protein Binding
D003172:Complement C1; D003174:Complement C1 Inactivator Proteins