For a sample containing both protein and nucleic acid, the absorbance measured a

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.

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=Cprotein280*protein280 + Cnucleic acid280*nucleic acid280

and A260=Cprotein260*protein260 + Cnucleic acid260*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

Explanation / Answer

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*protein260 = (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*protein280 = (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*nucleic 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*nucleic acid280 = (0.04 mg/ml)*(10.8cm-1M-1) = 0.432

Related Questions

Navigate

• Browse (All)
• Browse F
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.