Do you need the molar extinction coefficient of your drug substance protein?
The protein’s molar extinction coefficient depends on the actual protein sequence. It also depends on the content of UV absorbing amino acids, and the buffer composition. Fortunately, it is possible to determine it accurately.
The ICH Q6B Guidelines (Test Procedures and Acceptance Criteria for Biotechnological/Biological Products) requires the determination of the extinction coefficient of a protein. This blog post describes why it is important to determine it, regardless of whether you follow the ICH Q6B or not.
So why do you need to know the extinction coefficient of your drug substance protein? Because then you can use spectrophotometry and UV-absorption to determine the protein concentration in laboratory samples.
First we determine the exact quantity of protein by amino acid analysis. Then we prepare a dilution series of your protein and measure the UV absorbance at 280 nm at different protein concentrations. Finally, we calculate the molar extinction coefficient from the dilution series and the protein molecular weight.
You will receive:
- Determination of the molar extinction coefficient of your protein.
- Dilution series with UV absorbance at 280 nm as function of concentration.
- Quantitative amino acid analysis of your protein stock solution.
- Calculation of protein molecular weight from sequence.
- Analysis result in 2-3 weeks.
You are welcome to send us a request if you have specific analysis needs.