Non-Enzymic Decarboxylation of Methionine by Ferrous Ion

Abstract

IN work on the precursors of the volatile sulphur components of vegetable flavours and odours, a non-enzymic oxidative decarboxylation of methionine in the presence of Fe²⁺ was observed. The final reaction mixture had a very pronounced odour. Unlike other well-known Fe²⁺ oxidations, there was no need for added hydrogen peroxide^1,2 or ascorbic acid^3,4. The addition of a metal chelating agent such as ethylenediamine tetraacetate (EDTA) or citrate was very stimulatory. Table 1 shows the absolute requirement for Fe²⁺. Only Fe²⁺ was able to carry out this decarboxylation. Mg²⁺, Mn²⁺, Ca²⁺, Co²⁺, Ni²⁺, Zn²⁺, Cu²⁺ and Al³⁺ were completely ineffective. Fe³⁺ was 1 per cent as effective as Fe²⁺.