1. What is the Extinction Coefficient Calculator?

The Extinction Coefficient Calculator estimates peptide bond absorbance at 214 nm based on the extinction coefficient at 280 nm. This provides a practical method for protein quantification and analysis using UV spectrophotometry.

2. How Does the Calculator Work?

The calculator uses the extinction coefficient approximation formula:

Where:

• \( \varepsilon_{214} \) — Extinction coefficient at 214 nm (M⁻¹ cm⁻¹)
• \( \varepsilon_{280} \) — Extinction coefficient at 280 nm (M⁻¹ cm⁻¹)
• 0.66 — Approximation factor for peptide bond absorbance

Explanation: This approximation estimates the peptide bond absorbance extinction at 214 nm based on the known extinction coefficient at 280 nm.

3. Importance of Extinction Coefficient Calculation

Details: Accurate extinction coefficient calculation is crucial for protein quantification, concentration determination, and spectroscopic analysis in biochemical research and protein characterization.

4. Using the Calculator

Tips: Enter the extinction coefficient at 280 nm in M⁻¹ cm⁻¹. The value must be positive and valid for accurate calculation of the 214 nm extinction coefficient.

5. Frequently Asked Questions (FAQ)

Q1: Why use 214 nm for protein measurement?
A: 214 nm wavelength measures peptide bond absorbance, which is more universal across different proteins compared to aromatic amino acid absorbance at 280 nm.

Q2: How accurate is the 0.66 approximation factor?
A: This is an empirical approximation that works well for most proteins, but actual values may vary depending on protein composition and structure.

Q3: When should I use 214 nm vs 280 nm measurements?
A: Use 214 nm when proteins lack aromatic amino acids or for more universal quantification. Use 280 nm for proteins with known aromatic amino acid content.

Q4: What are typical extinction coefficient values?
A: Extinction coefficients vary widely by protein, typically ranging from thousands to hundreds of thousands M⁻¹ cm⁻¹ depending on size and composition.

Q5: Are there limitations to this approximation?
A: This approximation may be less accurate for proteins with unusual amino acid compositions or non-standard structures. For precise work, experimental determination is recommended.