1. What is the Protein Concentration Absorbance 280 Formula?

The formula estimates protein concentration from UV absorbance measurements at 280 nm and 260 nm. This method is widely used in biochemistry and molecular biology laboratories for quick and non-destructive protein quantification.

2. How Does the Calculator Work?

The calculator uses the protein concentration formula:

Where:

• \( A280 \) — Absorbance at 280 nm
• \( A260 \) — Absorbance at 260 nm
• 1.55 — Coefficient for A280 absorbance
• 0.76 — Coefficient for A260 absorbance correction

Explanation: The formula corrects for nucleic acid contamination (measured at 260 nm) to provide a more accurate protein concentration estimate based on aromatic amino acid absorbance at 280 nm.

3. Importance of Protein Concentration Measurement

Details: Accurate protein concentration measurement is essential for various applications including enzyme kinetics studies, protein purification, Western blotting, and ensuring consistent results in biochemical experiments.

4. Using the Calculator

Tips: Enter absorbance values at 280 nm and 260 nm. Ensure measurements are taken using a properly calibrated spectrophotometer with appropriate blank corrections. Values should be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why measure absorbance at both 280 nm and 260 nm?
A: Measuring at 260 nm helps correct for nucleic acid contamination, which can interfere with accurate protein concentration estimation at 280 nm.

Q2: What is the typical range for accurate measurements?
A: For best results, absorbance values should be between 0.1 and 1.0. Values outside this range may require sample dilution or concentration.

Q3: Are there limitations to this method?
A: This method assumes typical protein composition and may be less accurate for proteins with unusual amino acid compositions or high nucleic acid contamination.

Q4: How should samples be prepared for measurement?
A: Samples should be in a clear solution with appropriate buffer matching the blank. Turbid samples should be clarified by centrifugation or filtration.

Q5: Can this method be used for all protein types?
A: While generally applicable, proteins with very low aromatic amino acid content may require alternative quantification methods such as Bradford or BCA assays.