POLARIZATION FLUORESCENCE STUDIES ON PROTEOLYTIC ACTIVITY OF α2-MACROGLOBULIN-TRYPSIN COMPLEXES

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Abstract
When digestive enzymes are released into the blood, they may be completely inactivated by a variety of inhibitors present (.alpha.1-protease inhibitor, antithrombin III, .alpha.2-plasmin inhibitor, etc.) or only partially neutralized by .alpha.2-macroglobulin. In this study, polarization fluorescence is used to demonstrate that complexes of [human plasma] .alpha.2-macroglobulin with trypsin can digest .beta.-endorphin, ACTH and .beta.-lipotropin. A small trypsin inhibitor (trasylol, MW 6500) can prevent this digestion but larger inhibitory proteins (i.e., soybean trypsin inhibitor, MW 21,500; .alpha.1-protease inhibitor, MW 50,000) cannot.