Section 7
Chapter 6,836

Treatment of human complement c 4 and complement c 3 with amines or chaotropic ions evidence of a functional and structural change that provides uncleaved complement c 4 and complement c 3 with properties of their soluble activated forms complement c 4b and complement c 3b

Von Zabern, I.; Nolte, R.; Vogt, W.

Scandinavian Journal of Immunology 13(5): 413-432


ISSN/ISBN: 0300-9475
Accession: 006835920

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Treatment of human complement components C4 and C3 with amines like hydrazine, ammonium hydroxide and neutral ammonium salts or with chaotropic salts like KSCN and NaBr leads to complete loss of hemolytic activity. The pretreated componets are still active in formation of soluble C3 convertases. This activity pattern is reminiscent of the activities of C4 and C3 that have been activated by cleavage in the fluid phase. The antigenic properties of pretreated C4 and C3 are similar to soluble C4b and C3b. The polypeptide chain structure of pretreated C4 and C3 is identical to that of the untreated components when investigated by SDS [sodium dodecyl sulfate] gel electrophoresis. Pretreatment even reduces greatly the susceptibility of C4 to cleavage by .**GRAPHIC**. and of C3 to cleavage by classicial and altenative pathway C3 convertases. Pretreated components have lost the ability to combine with EAC1 [erythrocyte, antibody, C1] and EAC142, respectively; this fact explains their failure to exhibit hemolytic activity. In serum, pretreated C4 and C3 are cleaved in a manner similar to C4b and C3b. Amines and chaotropic ions cause the same functional structural alterations, which are best explained by assumption of a conformational change. A similar transformation can also occur in C4 and C3 during preparation or storage.

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