OBSERVATIONS ON THE CONFORMATIONAL-CHANGES IN THE STRUCTURE OF A CELL-SURFACE PROTEASE, FOLLOWED BY ITS ABILITY TO BE RECOGNIZED BY COMPETITIVE AND NONCOMPETITIVE INHIBITORS

Lung tumour cells possess a cell surface protease which can be inhibited by a cytoplasmic protein inhibitor extracted from these cells. The dissociation of this enzyme-inhibitor complex on the surface of tumour cells in sections treated with 10(-4) M sodium dodecyl sulphate has been studied. The dissociation of the inhibitor and repin of enzymic activity was followed by the use of a fluorescent probe which binds to the active centre of the cell surface enzyme in a competitive manner.