Immunoenzymology of acetylcholinesterase. IV. Studies on an enzyme-inhibiting antibody.

Abstract Inhibitory antibody was obtained from the serum of a rabbit immunized with AChE. This antibody differed from previously described noninhibitory antibody only in its effect on the hydrolysis of ATCh by AChE. Both inhibitory and noninhibitory antibody-enzyme complexes showed increased stability to heat and demonstrated similar activity and kinetic parameters with other substrates. When in complex with the enzyme, both the whole inhibitory IgG molecule and F(ab′) 2 fragments inhibited hydrolysis of ATCh and protected AChE from heat inactivation.