Supporting Information
Pheeney et al. 10.1073/pnas.1201551109
Fig. S1.
Absorbance spectrum of hemoglobin (5
μ
M) in phosphate buffer (5 mM phosphate, 5 mM NaCl, 40 mM MgCl
2
, 5 mM spermidine, and pH
7
) before
(solid) and after (dotted) electrocatalysis with MB-DNA.
Fig. S2.
Left
: The MB-DNA peak reduction potential as a function of pH, ranging from 5.5 to 8.5 in the absence of hemoglobin measured from the cyclic
voltammetry data (scan rate
¼
100
mV
∕
s).
Right
: The accumulated current for electrocatalytically amplified MB-DNA in phosphate buffer (5 mM phosphate,
5 mM NaCl, 40 mM MgCl
2
, and 5 mM spermidine) as a function of pH, ranging from 5.5 to 8.5, is presented. The accumulated current was determined from
chronocoulometry (V
¼
−
450
mV for 10 s) in the presence of 25
μ
M Hemoglobin.
Fig. S3.
Denaturation curve of hemoglobin (1
μ
M) measured by circular dichroism in phosphate buffer (5 mM phosphate, 5 mM NaCl, 40 mM MgCl
2
,5mM
spermidine, and pH 7). The molar elipticity was measured at 225 nm as the temperature was varied from 20 °C to 60 °C. An initial transition can be observed
from 32
–
35 °C and a larger transition at 45
–
56 °C corresponding to the denaturation of the alpha helices.
Pheeney et al.
www.pnas.org/cgi/doi/10.1073/pnas.1201551109
1of1