Protein Concentration Calculator 280 Abs Blood

Protein Concentration Equation:

\[ C = \frac{A_{280}}{(\epsilon \times l)} - BC \]

A280 (Absorbance):

dimensionless

Extinction Coefficient (ε):

ml mg^-1 cm^-1

Path Length (l):

Blood Correction (BC):

mg/ml

Protein Concentration (C):

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1. What is the Protein Concentration Equation?

The protein concentration equation adjusts the standard A280 measurement for blood contamination. It calculates protein concentration from absorbance at 280 nm while accounting for blood interference.

2. How Does the Calculator Work?

The calculator uses the equation:

\[ C = \frac{A_{280}}{(\epsilon \times l)} - BC \]

Where:

\( C \) — Protein concentration (mg/ml)
\( A_{280} \) — Absorbance at 280 nm (dimensionless)
\( \epsilon \) — Extinction coefficient (ml mg^-1 cm^-1)
\( l \) — Path length (cm)
\( BC \) — Blood correction factor (mg/ml)

Explanation: The equation first calculates the standard protein concentration from A280 measurement, then subtracts the contribution from blood contamination.

3. Importance of Protein Concentration Measurement

Details: Accurate protein concentration measurement is essential for experimental consistency, protein purification, and quantitative analyses in biochemistry and molecular biology.

4. Using the Calculator

Tips: Enter A280 value, extinction coefficient (typically 1.0 for most proteins at 1 mg/ml), path length (usually 1 cm for standard cuvettes), and blood correction factor (if applicable).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical extinction coefficient for proteins?
A: Most proteins have ε ≈ 1.0 ml mg^-1 cm^-1, but this varies. Antibodies typically have ε ≈ 1.4. Check literature for your specific protein.

Q2: When is blood correction needed?
A: Blood correction is needed when measuring protein concentration in samples that may contain hemoglobin or other blood components that absorb at 280 nm.

Q3: What path length should I use?
A: Standard cuvettes have 1 cm path length. For microvolume measurements, use the actual path length of your measurement system.

Q4: Are there limitations to this method?
A: This method assumes proteins are the main contributor to A280. Nucleic acid contamination or unusual amino acid composition can affect accuracy.

Q5: How do I determine the blood correction factor?
A: The blood correction factor can be determined experimentally by measuring A280 of known blood concentrations or from literature values for hemoglobin.