Fig. 5: Stochastic sensing of L-Glutathione by Au(III) embedded MspA-M.
a The chemical structure of L-Glutathione (GSH). GSH is a tripeptide containing a cysteine residue (blue labeled portion). b Reversible and sequential binding of GSH with [AuCl4]− embedded MspA-M. The demonstrated trace was recorded with a +100 mV applied voltage when 4 μM HAuCl4 in cis and 40 μM GSH in trans were present simultaneously. Resistive pulse signals in the trace represent GSH binding with the pore. Blue dots mark the events concerning GSH. Other unlabeled events are background signals as described in Supplementary Fig. 14. c A representative GSH blockage event. Characteristic jitter signals similar to that of Cys or Hcy can be recognized as state 1SH. However, the mean blockage amplitude of state 1SH for GSH is systematically deeper than that of Cys or Hcy. Gray and blue marked regions represent the the area that the transition of state 0–1 or state 1–1SH distributes respectively. d The scatter plot of ΔI/I0 vs the dwell time with the corresponding amplitude histogram from events of [AuCl4]− or GSH binding. The definition of ΔI and I0 is the same as that described in Fig. 3f. The statistical data in d were from a continuous 10 min recording as described in b. (Supplementary Tables 9 and 10). e Simultaneous discrimination of GSH and Cys with [AuCl4]− embedded MspA-M. Cys and GSH were placed in trans with a concentration of 10 μM and 30 μM, respectively. Whereas, the concentration of HAuCl4 in cis was kept at 4 μM. In the dotted box, a zoomed-in view of GSH and Cys events were demonstrated. Red triangles mark the events of Cys and blue dots mark those of GSH. The grey star marks binding events from one or two [AuCl4]−. f The scatter plot of the dwell time vs the ΔI/I0 with the corresponding amplitude histogram from the simultaneous recording of Cys and GSH as a mixture with 10 μM and 30 μM in trans, respectively. The statistical data were derived from a continuous 10 min recording.
