A Method for Preparing Monospecific Antisera to C1 Esterase (C1s): Microheterogeneity of Purified C1s

Abstract

Highly purified C1s has been obtained by immunization of rabbits using popliteal node injections of highly purified C1s followed by booster injections with gel segments containing C1s after disc-acrylamide gel electrophoresis. The antisera are monospecific and unexpectedly reveal electrophoretic microheterogeneity in highly purified C1s preparations. We have studied this electrophoretic heterogeneity in highly purified and in crude C1s preparations and hypothesize that it is due to two factors: 1) The partial proteolysis of C1s produced either by other serum enzymes or perhaps by autocatalysis. This can be demonstrated in highly purified C1s preparations. 2) The presence in crude preparations of another serum protein(s) which appears to influence the migration of C1s. These antisera are useful for quantitating C1s by single radial diffusion. We consider the heterogeneity of C1s to be an important feature of this molecule and future quantitative studies should take account of it.