Protein Assay- The Lowry method
Our group had done the experiment on Protein Assay as a method of determining protein concentration. The absorbance is at 750 nm.

Our group was using the spectrophotometer to determine the absorbance of the protein. The Lowry method depends on the presence of tyrosine within the protein to be measured. The standard protein must contain approximately the same number of tyrosine residues as the sample, or the procedure will be inaccurate. If there are no tyrosine residues in the sample to be measured, the Lowry method of protein determination is useless.

From the experiment that we had conducted, we record the data in table and from the data, we sketch the graph of it. Below are the data and the graph from that experiment:

our data:


our graph:


theoritical graph:



From our findings we can see that our result was different from the theoretical value. Our findings were inaccurate maybe due to the mistakes in measurement of protein and Lowry reagent 1 and 2. Furthermore, the way we handle the cuvec may have affected the value that we should gain. Plus, the solution may be affected by other substances like other chemical reagents. Thus, it’ll affect the absorbance since it is so sensitive.

DETERMINING CONCENTRATION OF PROTEIN IN EGGS
We had also done an investigation in testing samples of albumin from Grade A, Grade B and Grade C of chicken egg and also the albumin of the duck egg (X). We need to determine the concentration of protein in the egg. The result is shown below:




We can conclude that the duck egg has the highest protein concentration in its content. The grade does not indicate the amount of protein inside the egg, but the eggs were assorted due to their size and also the shell.

grades

D20071029523 What is it with Grade?

I think that the grade of an egg do not determines the protein content in it. The grading processes only examined for both interior and exterior quality and eggs are sorted according to size but not the protein content. Grade quality and the protein content are not related to one another. In descending order of quality grades are AA, A and B. From the previous experiment in the lab, I found that the A grade egg has lower protein content compared to B grade egg. The egg of ‘ayam kampung’ also has a higher content of protein compared to the A grade egg. Thus, this shows that the grade of an egg doesn’t indicate how much protein it has. The egg is a nutrient-dense food, containing high quality protein and a wide range of essential vitamins, minerals and trace elements. Therefore eggs can make a significant contribution to a healthy diet. We can eat eggs as they have many nutritional values, but too much intake will also cause health problem. As a conclusion, the grades of eggs do not determine the protein content in it.

References:
http://www.qualityegg.net/faq.html
edis.ifas.ufl.edu/PS020