title: Localization of the proteinase-induced thiol groups in alpha 2-macroglobulin.
abstract: Free thiol groups released on proteolytic attack of alpha 2-macroglobulin by trypsin or chymotrypsin bind covalently to thiopropyl-Sepharose, indicating that they are located at the surface of the complexes. These cysteine sulfhydryl groups appear to be in contact with the alpha 2M-bound proteases from singlet-singlet energy transfer measurements between fluorescein isothiocyanate-labeled proteinases and N-(iodoacetylaminoethyl)-5-naphtylamine-1-sulfonic acid-labeled thiols in alpha 2-macroglobulin.
mesh_terms: D001665:Binding Sites; D002846:Chromatography, Affinity; D002918:Chymotrypsin / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D004735:Energy Transfer; D006801:Humans; D011485:Protein Binding; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D013499:Surface Properties; D014357:Trypsin / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D013438:Sulfhydryl Compounds; D000511:alpha-Macroglobulins; D010450:Endopeptidases; D002918:Chymotrypsin; D014357:Trypsin