FIG. 2.

Fluorescence intensity as a function of time with cell-bound NBD-labeled PA. CHO-R1 ATR800 cells were incubated on ice with PA labeled with NBD at Cys305 or Cys306 and were then washed in the cold and suspended in cold medium. Cell suspensions (2 ml) were placed in the fluorimeter at time zero. The cuvette chamber was thermostated at 37°C, and the fluorescence intensity was recorded at 544 nm. (a) Cell-bound NBD-labeled PA G305C; (b) NBD-labeled PA G305C in solution; (c) cell-bound NBD-labeled PA N306C.