FIG. 8.

Effect of EDTA on the degradation of insoluble R22 ECM labeled with [³⁵S]methionine-cysteine and [³H]proline by plasmin-coated B. burgdorferi. ECM components were labeled preferentially with [³⁵S]methionine-cysteine (noncollagenous protein) and [³H]proline (collagen). Spirochetes were incubated in HBSS with no additions (B-UT) and with addition of PLG and uPA together in HBSS to form spirochete surface-associated plasmin (B-Plasmin). Spirochetes were added to tissue culture plate wells containing ECM in the absence and in the presence of EDTA and then incubated for 6 h. Released (supernatant) and unreleased (2 N NaOH digest of undegraded ECM) radioactivity was counted for each well. Percent release of the total radioactive counts present in each well was calculated as described in Materials and Methods. Bars represent mean percent radioactivity release ± standard deviation of three replicate wells per experimental group. The experiment was performed twice with similar results.