1. What is RNA Extinction Coefficient?

The RNA extinction coefficient (ε) is a measure of how strongly RNA molecules absorb light at 260 nm wavelength. It is used to quantify RNA concentration in solution and is calculated based on the nucleotide composition of the RNA sequence.

2. How Does the Calculator Work?

The calculator uses the RNA extinction coefficient formula:

Where:

• \( \varepsilon_{RNA} \) — RNA molar extinction coefficient (M⁻¹ cm⁻¹)
• \( \varepsilon_{nucleotides} \) — Extinction coefficient per nucleotide base
• \( correction \) — Correction factor for experimental conditions

Standard nucleotide extinction coefficients:

• Adenine (A): 15,400 M⁻¹ cm⁻¹
• Cytosine (C): 7,500 M⁻¹ cm⁻¹
• Guanine (G): 11,700 M⁻¹ cm⁻¹
• Uracil (U): 9,900 M⁻¹ cm⁻¹

3. Importance of RNA Extinction Coefficient

Details: The extinction coefficient is essential for accurate RNA quantification using spectrophotometry. It allows researchers to determine RNA concentration from absorbance measurements at 260 nm, which is crucial for molecular biology experiments, RNA sequencing, and gene expression studies.

4. Using the Calculator

Tips: Enter the count of each nucleotide (A, C, G, U) in your RNA sequence. The correction factor accounts for experimental variations and is typically 1.0 for standard conditions. All values must be non-negative integers for nucleotide counts.

5. Frequently Asked Questions (FAQ)

Q1: Why is the extinction coefficient important for RNA quantification?
A: It converts absorbance readings at 260 nm into molar concentration, allowing accurate determination of RNA amount in solution.

Q2: How do I measure RNA concentration using the extinction coefficient?
A: Concentration (M) = A₂₆₀ / (ε × path length in cm). For standard 1 cm path length: Concentration = A₂₆₀ / ε.

Q3: What factors affect the extinction coefficient?
A: Nucleotide composition, RNA secondary structure, pH, temperature, and buffer conditions can influence the actual extinction coefficient.

Q4: How does RNA differ from DNA in extinction coefficients?
A: RNA uses uracil instead of thymine, and the extinction coefficients for individual nucleotides differ between RNA and DNA.

Q5: When should I use a correction factor other than 1.0?
A: Use correction factors for non-standard conditions, such as different temperatures, pH values, or when using modified nucleotides.