Interaction of Zn2+ with guinea-pig C5 convertase and guinea-pig C5

• Published in: Molecular immunology Vol. 21; no. 1; p. 69
• Main Authors: Evans, B D, Amiraian, K
• Format: Journal Article
• Language: English
• Published: England 01.01.1984
• Subjects: Animals; Complement Activating Enzymes - immunology; Complement Activation - drug effects; Complement C2 - immunology; Complement C3-C5 Convertases; Complement C5 - immunology; Guinea Pigs; Humans; Kinetics; Zinc - pharmacology
• ISSN: 0161-5890; 1872-9142
• DOI: 10.1016/0161-5890(84)90091-9

A comparison of two methods of C5 activation, the standard method (EAC14 + C2, C3, C5, C6, and C7) and the washed-cell intermediate method (EAC1423 + C5 and washed), demonstrated that formation of hemolytically competent SAC14235 was reduced in the washed-cell method. Addition of Zn2+ in this method increased the formation of competent SAC14235 to the approximate level of the standard method. The optimum concn range of Zn2+ was 0.006-0.025 mM. In the standard method Zn2+ had no significant enhancing effect on the formation of competent SAC14235. Zn2+ had a greater affinity for EAC1423 than for fluid-phase C5 when reacted with each separately. Maximum enhancement, however, was obtained when Zn2+ was present during the reaction of C5 with EAC1423. The effect of Zn2+ on C5 activity was not related to the stabilizing property of C6 on cell-bound C5. In the washed-cell method there was an inverse relationship between the concn of C2 or C3 and the concn of C5 required to generate one competent SAC14235/cell. Over a 10-fold range of C2 or C3 concn there was an approximate four-fold increase in the number of competent SAC14235/cell formed in the presence of Zn2+. Zn2+ enhances formation of competent SAC14235 on cells that have a limited ability to activate C5 even though the C2 and C3 on the convertase are present in excess.