Alpha 2 Macroglobulin, Human Plasma, Fast Form

Alpha 2 Macroglobulin (A2M) is a plasma protease inhibitor which has been shown to exist in two forms. The Slow Form of A2M (S-A2M) is the form which possesses the ability to bind and inhibit proteases by a “trap” method. The Fast Form of A2M (F-A2M) is generated when S-A2M undergoes a conformational change due to either entrapment of a protease in the A2M bait region, or chemical cleavage of an internal thiol ester bond located near the bait region. F-A2M does not possess the ability to bind and inhibit protease activity. F-A2M is rapidly taken up by the liver, with a half-life of 2-4 minutes. In vivo, F-A2M typically represents only 0.17–0.7% of the total A2M in blood plasma of adults. The F-A2M plasma concentration is, however, increased in many disease states including pancreatitis, multiple sclerosis and sepsis. F-A2M has also been implicated in the inhibition of amyloid formation associated with Alzheimer’s disease and spongiform encephalopathy.