The reactivity of EDTA, copper ion, and copper citrate with metallothioneins isolated from the digestive gland of cadmium-contaminated lobster (Homarus americanus)

Abstract

The reactivity of EDTA, Cu2+, and copper citrate with two metallothionein preparations (MT-1 and MT-2) isolated from the digestive gland of Cd-contaminated American lobster (Homarus americanus) was studied. Under pseudo-first-order conditions, metallothioneins reacted with EDTA for removal of Cd2+ in a multiphasic manner. Cadmium(+II) removal by Cu2+ was complex and non-stoichiometric, suggesting different binding sites. Rabbit liver metallothionein reacted similarly. Cadmium removal from lobster metallothionein by copper citrate was slow and triphasic in nature. EDTA removed Cu2+ from lobster metallothionein very slowly.