Abstract
Summary
A relatively vigorous oxygen consuming, non-enzymic reaction occurs at physiological temperatures between p-phenyl-enediamine (PPDA) and dihydroxyphenylalanine (DOPA) when the 2 compounds are mixed in aqueous solution at pH 7.0 to 7.5, with maximum activity, based on oxygen consumption, obtained at a DOPA-PPDA molecular ratio of approximately 2:1. The reaction has been studied manometrically with pure compounds and with various melanoma components, such as are contained in mouse melanoma extract and in plasma and urine from patients with disseminated malignant melanoma. The oxidation observed with various melanoma components is thought to be identical or analogous to the PPDA-DOPA reaction found with the pure substances since in all instances the reaction is both KCN and heat insensitive. Preliminary data are given to illustrate the possibilities of exploiting such reactions for diagnostic and chemotherapeutic purposes.
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