Study of electrolytic labeling of fibrinogen with 131iodine by sephadex G-10 gel filtration

Abstract

The labeling of human fibrinogen with 131I by the electrolysis technique of Rosa and coll. 2 was studied by Sephadex G-10 gel filtration of the product. Because fibrinogen may not be labeled in excess of 0.5 atoms of iodine per molecule fibrinogen, it was necessary to use a smaller amount of carrier iodide in the electrolytic cell than in the original method. Under these circumstances, there was a high side reaction of oxidation of iodide probably to iodate, resulting in a very low iodination yield. Under defined conditions of iodide concentration, pH and duration of electrolysis, a satisfactory product was prepared. Together with gel filtration, this method offers an accurate and elegant procedure for the preparation of iodinated proteins under controlled conditions. Prepared by this method, iodinated human fibrinogen had a biological half-life ( t 1 2 ), in turnover studies, of approximately 3.6 days in normal subjects, while in subjects suffering from venous thrombosis this half-life was markedly shortened to a mean value of 2.5 days.