METAL CHELATE REACTION OF ENTEROCHROMAFFIN

Abstract

Enterochromaffin slowly binds ferrous ions at pH levels between 3.5 and 5.0 and gives them up again at low pH levels (1-2.5). Ferrous ions so bound may be demonstrated in situ by action of potassium ferricyanide, probably by acid dissociation of the chelate complex and precipitation of Turnbull's blue. This reaction is prevented by acetylation and tosylation, in agreement with the azo reaction. It is prevented by drastic oxidations but not by milder, sufficient to prevent azo coupling.