Characteristics of a ferrous iron complex of L-epinephrine.

IN the course of studying the inhibition of the liver tyrosine oxidase system by L-epinephrine and analogsl the desirability of prpearing a ferrous complex of this hormone became apparent . Although Although such a complex has been described empirically in stucües of the effects of cations and anions on .the the oxidation of catecholamines2 4 and by Yogeler5 , no attempts have been reported to characterize the complex. The complex can be prepared as follows : molar amounts of Lepiaephrine and FeC12 (2 :1) are weighed into a beaker at 25°C, about 30-60 ml distilled water are added per 10 mmoles FeC12. The pH is rapidly adjusted to 7.0 with a motor driven stirrer and the purple solution is stirred at room temperature for 5 min. Several volumes of chilled acetone are added, the precipitate is filtered on a Huchner funnel with suction, and washings are made with cold acetone . The dark purple solid is dried in vacuo in a dessicator and is relatively stable in the dry form. Titratioas of L-epinephrine with various amounts of FeC12 are illustrated by Fig . l . Titratioas were carried out in aqueous solutions using the Leeds and Northrup line operated pH meter (Model 7664) and a miniature glass silver chloride type electrode assembly . The titratioas were conducted in a nitrogen atmosphere at 25°C . The pH meter was standardized with Fisher buffers at pH 4.0, 7.0 and 9.0 . Back titration of epinephrine revealed only very small changes in the titration curve so that decomposition of the hormone was minimized under these conditions . Comparison of curves 1 and 2 suggests that the secondary amino group of epinephrine is not involved is the complex so that the ionized phenolic group probably directs the positioning of the metal indicative of the structure on page 511 (structure I) .