Supporting information
Fig.1S. (A) Effects of different concentrations of D-cysteine (D-Cys) and L-cysteine (L-Cys) up to
7.5 mM on luciferase bioluminescent signal (7.5 mM L-Cys, closed square;7.5 mM D-Cys, closeddiamond; 5
mM L-Cys, closed triangle; 5 mM D-Cys, closed circle; 2.5 mM L-Cys, dashed line; 2.5 mM D-Cys, solid line;
control, open square). (B) Effects of 15 and 25 mM concentrations of D-cysteine (D-Cys) and L-
cysteine (L-Cys) on luciferase bioluminescence signal. A 20 µl of each concentration of D-Cysor LCyswas added 15 seconds after the initioation of reaction to 180 µl reaction mixture include 0.03 µg (0.03
mg.ml-1) luciferase, 0.25 mM D-luciferin, 1.5 mM ATP, 6 mM MgSO4, 30 mM Tris-HCl buffer (pH 7.8)
and the signal variations of luciferase were recorded by luminometer during 20 minutes at 25 °C. (15 mM
L-Cys, closed square;15 mM D-Cys, closeddiamond; 25 mM L-Cys, closed triangle; 25 mM D-Cys, dashed line;
control, solid line)
Fig.2S.Effects of D-cysteine (D-Cys), L-cysteine (L-Cys), beta-mercaptoethanol (BME), ditiotreitol
(DTT), and coenzyme A (CoA) on reactivation of heat-inactivated luciferase. 20 µl luciferase
inactivated at 53 °C for 5 min, cooled on ice for 5 min and subsequently 10 µl (0.2 mg.ml-1) of the
inactivated-cooled enzyme added to 40 µl mixture include 0.25 mM D-luciferin, 1.5 mM ATP, 6 mM
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MgSO4, 30 mM Tris-HCl buffer (pH 7.8) and 6 mM of each of D-Cys, L-Cys, BME, DTT and CoA.
Experiments were carried out in presence of these compounds and rates of reactivation over time were
measured with luminometer (Berthold Detection System, Germany) at 25 °C (pH 7.8). Readings were
taken every 20 seconds (CoA, closed triangle; L-Cys, closed diamond;DTT, dashed line; BME, open square;DCys, closed square; control, closed circle).
Fig.3S. The effect of L-cysteine on luciferase aggregation size. 50µl (1µM) of heat-inactivated
luciferase sample at 53 °C for 5 min was added to 950 µl Tris-HCl buffers in the absence (a) and presence
(b) of 5 mM L-cysteine. The average aggregate size and the polydispersity of the aggregate-size
distribution were determined by dynamic light scattering (DLS).
Fig.4S.The effect of D-cysteine on luciferase aggregation size.50µl (1µM) of heat-inactivated
Luciferase sample at 53 °C for 5 min was added to 950 µl Tris-HCl buffers in the absence (a) and
presence (b) of 5 mM D-cysteine. The average aggregate size and the polydispersity of the aggregate-size
distribution were determined by dynamic light scattering (DLS).
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