Metabolic Turnover Studies on the Two Major Forms of Rat and Rabbit Plasminogen

Two major forms of plasminogen can be isolated from the plasmas of several species by affinity chromatography methods. These two forms are easily isolated in high purity from a single small animal, a situation which is particularly suitable for biological investigations. This paper shows that the two forms of rat and rabbit plasminogen must exist as such in the circulating plasma, are not interconvertible, and appear in the plasma at different rates following a single injection of l-[4,5-3H]leucine. Studies on the biological turnover characteristics of each major plasminogen form under homologous and heterologous conditions demonstrate that plasminogen Form 2 from affinity chromatography columns possesses a circulatory half-life which is slightly lower than plasminogen Form 1.