I need to find a way to measure protein concentration.

It's for part of my infection and immunity lab report.

We've done about radial immunodiffusion calculating the concentration of bovine serum albumin in unknown samples, and the last question is:

What other techniques could you use to measure the concentration of an antigen in a biological sample?

For some reason under this I have written: 'Specific protien concentrations' I guess this was because the lecturer mentioned it when the work was set and it makes sense antigens have protiens on so if I could work out the concentration of the protein then I'm there but I'm not sure how to do that?

Does anyone know of a way?

I also thought of a titration because that's how we always found the concentration of stuff back when did chemistry, so that would be titrating antibody against antigen, but I would need an indicator and I don't know of any.

Can anyone help me please?

Ballet_Baibe

Certainly! There are several techniques commonly used to measure protein concentration in a biological sample. Here are a few options:

1. Bradford Assay: This is a colorimetric assay in which the absorbance of a dye (such as Coomassie Brilliant Blue) changes upon binding to proteins. By comparing the absorbance of an unknown sample to a standard curve, the protein concentration can be determined.

2. Bicinchoninic Acid (BCA) Assay: Similar to the Bradford assay, the BCA assay also relies on the colorimetric reaction between proteins and a copper-based reagent. The intensity of the color produced is proportional to the protein concentration.

3. Lowry Assay: This biochemical assay uses the reaction between proteins and a mixture of reagents containing copper ions and Folin-Ciocalteu reagent. The resulting blue color can be measured spectrophotometrically to determine protein concentration.

4. Spectrophotometry: This method relies on the absorption of light by proteins. Proteins typically have a strong absorption peak at 280 nm due to the presence of aromatic amino acids (tyrosine and tryptophan). By measuring the absorbance of the sample at this wavelength, protein concentration can be estimated.

5. ELISA (Enzyme-Linked Immunosorbent Assay): This is a widely-used technique that involves the use of specific antibodies to detect and quantify proteins. The intensity of the signal generated is directly proportional to the protein concentration.

Regarding your idea of using titration, while titration can be used to determine the concentration of certain substances, it may not be the most suitable method for protein concentration measurement. Indicators used in acid-base titrations may not be applicable for detecting protein-protein interactions. Additionally, the complexity of biological samples may introduce challenges in titration methods.

For protein concentration measurements, it is generally recommended to use one of the aforementioned analytical techniques. Each method has its advantages and limitations, so it is important to select the method that is most suitable for your specific sample and experimental conditions.

I hope this helps! Let me know if you have any further questions.