1. What Is Protein Concentration Calculation?

Protein concentration calculation from absorbance is a fundamental technique in biochemistry that allows researchers to quantify protein content in a solution using spectrophotometric measurements.

2. How Does The Calculator Work?

The calculator uses the standard formula:

Where:

• Conc — Protein concentration in milligrams per milliliter (mg/mL)
• Abs — Absorbance reading in absorbance units (AU)
• Factor — Calibration factor specific to the assay (mg/mL per AU)

Explanation: This calculation is based on the Beer-Lambert law, which states that absorbance is proportional to the concentration of the absorbing substance in solution.

3. Importance Of Protein Quantification

Details: Accurate protein quantification is essential for various applications including enzyme kinetics studies, protein purification, clinical diagnostics, and pharmaceutical development.

4. Using The Calculator

Tips: Enter the absorbance value measured from your spectrophotometer and the appropriate factor for your specific assay. Ensure measurements are taken at the correct wavelength (typically 280nm for direct UV measurement or the specific wavelength for colorimetric assays).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical factor value for Bradford assay?
A: For Bradford assay, the factor typically ranges from 0.8 to 1.2 mg/mL per AU, but should be determined experimentally for each protein standard.

Q2: Why use different factors for different proteins?
A: Different proteins have varying extinction coefficients due to differences in aromatic amino acid content, requiring specific calibration factors for accurate quantification.

Q3: What is the linear range for absorbance measurements?
A: Most spectrophotometric assays are linear in the absorbance range of 0.1-1.0 AU. Samples outside this range should be diluted or concentrated accordingly.

Q4: How do I determine the factor for a new protein?
A: Create a standard curve using known concentrations of your purified protein and determine the factor from the slope of the absorbance vs. concentration plot.

Q5: Can I use this for other biomolecules besides proteins?
A: While the principle is similar, different biomolecules require specific assays and factors. This calculator is specifically designed for protein quantification.