FIG. 6.

Kinetics of release of radiolabeled, insoluble R22 ECM components by plasmin-coated B. burgdorferi. ECM components were labeled preferentially with [³⁵S]methionine-cysteine (noncollagenous protein), [³H]fucose (glycoprotein), and [³H]proline (collagen). Spirochetes were incubated with PLG and uPA together, in HBSS, to form spirochete surface-associated plasmin. Tissue culture plate wells containing ECM labeled with [³⁵S]methionine-cysteine (■), [³H]fucose (▴), and [³H]proline (●) were incubated with 10⁸ plasmin-coated spirochetes per well. At fixed intervals (0.5, 1, 2, 4, and 6 h), released (supernatant) and unreleased (2 N NaOH digest of undegraded ECM) radioactivity were counted for each of five replicate wells. Percent release of the total radioactive counts present in each well was calculated as described in Materials and Methods. Chart points represent the mean percent radioactivity release (minus the experimental background [mean value for wells that received HBSS alone]) ± standard deviation of five replicate wells per experimental group per time point. The experiment was performed twice with similar results.