title: Increase in the susceptibility of hemoglobin to trypsin on treatment with glutathione or cysteine.
abstract: 1. Native human hemoglobin A was digested with proteases after treatment with reduced or oxidized glutathione, cysteine, or cystine. 2. The treatment of hemoglobin with a 40-fold molar excess of reduced glutathione or cysteine at 37 degrees C for 4 enhanced its susceptibility to trypsin 4 or 6 times, respectively. However, oxidized glutathione and cystine had little or no effect on its susceptibility to the protease. 3. The enhanced susceptibility was not due to conformational change in hemoglobin, such as dissociation to dimers or monomers, or to unfolding of alpha-helical structure, but was due to dissociation of heme from the globin moiety, judging from measurements of the absorption spectrum and circular dichroism spectrum, and gel-filtration analysis.
mesh_terms: D001665:Binding Sites; D003545:Cysteine; D003553:Cystine; D005914:Globins; D005978:Glutathione; D006418:Heme; D006441:Hemoglobin A; D006801:Humans; D007700:Kinetics; D010084:Oxidation-Reduction; D011485:Protein Binding; D011487:Protein Conformation; D014357:Trypsin
chemical_list: D006418:Heme; D003553:Cystine; D005914:Globins; D006441:Hemoglobin A; D014357:Trypsin; D005978:Glutathione; D003545:Cysteine