FIG. 2.
Role of position 257 and potential disulfide bond formation in IgG endopeptidase activity of Mac-2 and Mac-2 mutant proteins. (A) In the upper panel, purified Mac-2M28 and Mac-2M28C257Y were incubated with myeloma IgG1 and IgG cleavage activity was analyzed by SDS-PAGE. The lower panel shows quantification of Mac-2M28 and Mac-2M28C257Y enzymatic activity using 125I-IgG as the substrate. *, P < 0.01 by Student's t test. (B) In the upper panel, purified Mac-2M8 and Mac-2M8Y257C were incubated with myeloma IgG1 and IgG cleavage activity was analyzed by SDS-PAGE. The lower panel shows quantification of Mac-2M8 and Mac-2M8Y257C enzymatic activity using 125I-IgG as the substrate. **, P < 0.01 by Student's t test.