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4) In biochemistry, we use a Bradford Assay to calculate the concentration of protein in a sample. This method uses the same principles of the standard curve from this experiment. In a Bradford Assay, a standard curve is prepared using a known protein, typically Bovine Serum Albumin (BSA), but rather than measuring the density, we can measure a different property -its absorbance. The graph below is representative of a standard curve from a Bradford Assay (with the line equation displayed on the graph). Bradford Assay Standard Curve 0.7 0.6 y 0.0004x 0.0097 0.5 0.4 a 0.3 0.2 0.1 200 400 600 800 1000 1200 1400 1600 1800 BSA protein concentration (ug/mL) Use the line equation given in this graph and calculate the concentration of protein in a sample that has an absorbance of 0.35. Show your calculation and be careful with units.

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Answer #1

Ans:- The Bradford protein assay is a spectroscopic analytical procedure used to measure the concentration of protein in a solution. In order to find a standard curve , one must use varying concentration of BSA in order to create a standard curve with concentration plotted on the x-axis and absorbance plotted on the y-axis. This curve is used to determine the concentration of the unknown protein.

From the graph we can obtain the equation of the line y=mx+b ,with R2 value as close to 1 as possible. R represents the sum of the square values of the fit substracted from each data point .

Here y= absorbance

m=slope

x= concentration

In the given question we are to use the line equation

y=0.350

b=0.0097

given equation y=0.0004x +0.0097

0.350=0.0004x+0.0097

x= 0.350-0.0097/0.0004

   =850.75 ug/ml

the concentration at an absorbance of 0.35 is 850.75ug/ml

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Answer #2

According the given plot, the equation for the curve is as follows: y 0.0004x+0.0097 Where, y represents the absorption and x represents the protein concentration. The unit of protein concentration is ug/mL and absorption is unitless Given that, value of absorbance, y=0.35 Calculate the value of x, the concentration of protein, using the equation (I), as follows: y 0.0004x+0.0097 0.0004x y-0.0097 yy-0.0097 岌 0.0004 0.35-0.0097 0.0004 850.75 ug/mL Hence, the concentration of protein is 850.75 ug/mL at the absorbance value of 0.35

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