Question

For a sample containing both protein and nucleic acid, the absorbance measured at a particular wavelength will be the sum of contributions from both types of molecule. Using the protein and nucleic acid concentrations you calculated in the previous step, calculate how much of the absorbance of the BSA and E.coli extract comes from protein and how much from nucleic acid, at each wavelength. HINT: the values in the table provided, are in essence, extinction coefficients with the units (mg/ml)^-1cm^-1.

	A260	A280
protein	0.512	0.894
nucleic acid	22.1	10.8

There was a question previous to this, and I calculated that my protein concentration is 0.58 mg/ml and that my nucleic acid concentration is 0.04 mg/ml.

this is what I have come up with so far, but I am not sure if it is correct, and am not sure how to use it to determine how much absorbance is from protein or nucleic acid.

A₂₈₀=C_protein280*ε_protein280 + C_{nucleic acid280}*ε_{nucleic acid280}

_and A₂₆₀=C_protein260*ε_protein260 + C_{nucleic acid260}*ε_{nucleic acid260}

A₂₈₀=(0.58 mg/ml)*(0.894cm^-1M^-1) + (0.04 mg/ml)*(10.8cm^-1M^-1)

A₂₈₀=0.51852+0.432

A₂₈₀=0.95052

and A₂₆₀=(0.58mg/ml)(0.512 cm^-1M^-1) + (0.04 mg/ml)*(22.1 cm^-1M^-1)

A₂₆₀=0.29696+0.884

A₂₆₀=1.18

Answer 1

Wee need to calculate following
(1) How much of the absorbance of the BSA and E.coli extract comes from protein at wavelength 260
(2) How much of the absorbance of the BSA and E.coli extract comes from protein at wavelength 280
(3) How much of the absorbance of the BSA and E.coli extract comes from nucleic acid at wavelength 260
(4) How much of the absorbance of the BSA and E.coli extract comes from nucleic acid at wavelength 280

The calculations are as shown.
(1) How much of the absorbance of the BSA and E.coli extract comes from protein at wavelength 260
Cprotein260*εprotein260 = (0.58mg/ml)(0.512 cm-1M-1)=0.29696

(2) How much of the absorbance of the BSA and E.coli extract comes from protein at wavelength 280
Cprotein280*εprotein280 = (0.58 mg/ml)*(0.894cm-1M-1) = 0.51852

(3) How much of the absorbance of the BSA and E.coli extract comes from nucleic acid at wavelength 260
Cnucleic acid260*εnucleic acid260 = (0.04 mg/ml)*(22.1 cm-1M-1)=0.884

(4) How much of the absorbance of the BSA and E.coli extract comes from nucleic acid at wavelength 280
Cnucleic acid280*εnucleic acid280 = (0.04 mg/ml)*(10.8cm-1M-1) = 0.432