Protective role of a lipocalin family protein C8 gamma against heavy metal toxicity: Characterization of the binding mode between C8 gamma and heavy metals

Abstract

Complement component 8γ (C8γ) is a member of lipocalin and its function is unclear. We have reported C8γ can bind to triphenyltin (TPT) and may affect the toxicity of TPT. Here, we evaluated the affinity of several substances to C8γ. By utilizing RI-labeled TPT, K_d value to C8γ was estimated as 56.2 nM. Competitive assay revealed tributyltin (TBT) can also bind to C8γ and mono- or di-substituted tin compounds showed weaker affinity. Triphenylarshine did not bind to C8γ and triphenyllead showed higher affinity than TPT. These results may shed light on a part of detoxification mechanisms by C8γ.