Why certain analysis results must be per mg protein

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Mie
Mie's picture
Why certain analysis results must be per mg protein

I've a question regarding analysis that needs to be per mg protein

Example: After we get results from TBARS assay, the results have to be per mg protein.

Can u help me in finding the reason why we have to take the results and divide it with the amount of protein that we get? Whats the connection between the results and protein?

i'm sorry but I hope u'll get the message. TQ

Sami Tuomivaara
Sami Tuomivaara's picture
Mie,

Mie,

If you do TBARS (or any other) assays for 5 and 10 mg of protein for two otherwise identical samples (for example two aliquots taken from the same plasma protein sample) you'll get twice as high result from the 10 mg sample compared to the 5 mg sample. Now, the samples are identical but the results are not, which is troublesome...

If you divide the assay results with the total protein amount, you normalize the result, in this case to 1 mg of protein. This way, the final value (result per mg of protein) will be the same for two identical samples no matter how much protein was used in the assays. You don't always have the same amount of protein available for assaying, so reporting the normalized result allows comparison of results between different samples.

If the samples you compare are different (for example normal versus stressed mice), the ratio of the results after normalization is directly proportional to the property (for example oxidative stress) you assay...

This practise is very common in quantitative analysis. In fact, results most often do not make sense at all without normalization.

Cheers,

Mie
Mie's picture
Tq. Sory for the late reply.

Tq. Sory for the late reply. If I have more question i will post again.