Fig. 5.

Kinetic NHX results. Predeuterated native WT Cyt c was exposed to a 75-ms H labeling pulse at high pH and 20°C, then quenched to slow HX conditions and analyzed by 2D NMR (20). The labeling of the foldon markers is shown in bold. The black curve depends on the rate for formation of a stable high pH intermediate (measured by CD and fluorescence) and shows the EX1 labeling that would be obtained during the 75-ms pulse caused by unfolding to this state. Comparison of the EX1 labeling of the markers for the different foldons at given pH values shows that the kinetic order for unfolding of the different foldon units is first red, then yellow, then green, and finally blue.