Effect of metals on the hyaluronidase inhibitor of human serum

Summary o 1. The influence of a number of cations on the serum inhibitor of hyaluronidase has been investigated. Both Mg ++ and Co ++ strongly activate, and Zn ++, Ni ++ and Mn ++ inactivate the inhibitor. Ca ++, Sr ++ and Ba ++ have no effect. The complex ion [Co(NH 3) 5Cl] ++ is an activator of the inhibitor, [Co(NH 3) 5H 2O] +++, [Co(NH 3) 6] +++ and vitamin B 12 are without effect. Be ++ and Li + activate the inhibitor to a small extent. 2. It is suggested that interionic forces extending beyond the coordination sphere of the cation are concerned in the process of activation of the inhibitor.