NanoPhotometer
®
NP80/N60/N50/C40
User Guide Version 3.1
58
Table 3. Protein extinction coefficients (
ε
prot
)
Type
ε
prot
[ g* cm/l]
Ext. Coeff. [l/g*cm]
Mol. Ext. Coeff. [M
-1
*cm
-1
]
MW [g/mol]
BSA
1.50
0.667
44,289
66,400
SA Mouse
1.49
0.670
44,220
66,000
SA Human
1.72
0.582
40,370
69,365
IgG Mouse
0.71
1.400
224,000
160,000
IgG Human
0.74
1.360
204,000
150,000
IgE Human
0.65
1.530
290,700
190,000
Lysozyme
0.38
2.640
37,984
37,984
OD1
1.00
N/A
N/A
N/A
Dye-labeled Protein UV280 Concentration
For dye-labeled proteins, the concentration of the protein is calculated using a modified form of
the Beer-Lambert equation. For these calculations, the instrument considers the absorption
maximum of the dye, and a certain dye-specific correction factor at 280 nm (see Table 4). The
dye concentration is calculated with or without background/dye correction for are as follows:
With background and with dye correction:
C =
�
A
280
−
A
BKG
−
cf
dye
*
�
A
max,dye
−
A
BKG
��
*
ε
prot
* Ð
With background and without dye correction:
C = (A
280
−
A
BKG
) *
ε
prot
* Ð
Without background and with dye correction:
C =
�
A
280
−
cf
dye
* A
max,dye
�
*
ε
prot
* Ð
Without background and without dye correction:
C =
A
280
*
ε
prot
* Ð
C
Concentration in mg/ml
A
280
Absorbance at 280 nm (10 mm path)
A
BKG
Absorbance at selected background wavelength (10 mm path)
A
max,dye
Absorbance value at the absorbance maximum of the dye (10 mm path)
ε
prot
Extinction coefficient/protein factor in g*cm/l
cf
dye
Dye-dependent correction factor at 280 nm
Ð
Dilution factor
Dye Concentration
For dye-labeled proteins, the concentration of the dye is calculated using a modified form of the
Beer-Lambert equation. For these calculations, the instrument considers the absorption
