title: Structural arrangement in the alpha 2-macroglobulin--thrombin complex.
abstract: The cysteine sulfhydryl groups of alpha 2-macroglobulin (alpha 2M) generated upon thrombin complex formation are in contact with the proteinase surface as evidenced by singlet--singlet energy transfer measurements from N-(iodoacetylaminoethyl)-5-naphthylamine-1-sulfonic acid-labeled thiol functions of alpha 2M to fluorescein isothiocyanate-labeled thrombin. The thrombin-alpha 2M binding is normally covalent, but the presence of hydroxylamine during the reaction leads to the formation of a non-covalent complex. The transfer energy determinations show that the alpha 2M binding sites of thrombin are quite similar, whatever covalent or non-covalent binding occurs.
mesh_terms: D002918:Chymotrypsin / Q000378:metabolism; D004735:Energy Transfer; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D013917:Thrombin / Q000378:metabolism*; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D000511:alpha-Macroglobulins; D002918:Chymotrypsin; D013917:Thrombin