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Protein Concentration Formula:
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The protein concentration formula estimates protein concentration from absorbance at 280 nm (A280). This method is based on the absorbance properties of aromatic amino acids (tryptophan and tyrosine) in proteins.
The calculator uses the protein concentration formula:
Where:
Explanation: The formula provides an estimate of protein concentration based on the UV absorbance of proteins at 280 nm wavelength.
Details: Accurate protein concentration measurement is crucial for protein purification, biochemical assays, drug development, and various research applications in molecular biology and biochemistry.
Tips: Enter the absorbance value measured at 280 nm. The value must be positive and typically ranges from 0.001 to 2.0 for accurate measurements.
Q1: Why use A280 for protein concentration measurement?
A: A280 measurement is a quick, non-destructive method that doesn't require additional reagents, making it ideal for routine protein quantification.
Q2: What are the limitations of this method?
A: The method assumes an average extinction coefficient and may be less accurate for proteins with unusual amino acid compositions or in the presence of nucleic acids.
Q3: When should this method not be used?
A: Avoid using this method when samples contain significant amounts of nucleic acids or other compounds that absorb at 280 nm.
Q4: How accurate is the 1.55 conversion factor?
A: The 1.55 factor provides a reasonable estimate for most proteins, but for precise measurements, protein-specific extinction coefficients should be used.
Q5: What is the typical range for protein concentration measurements?
A: This method is generally reliable for protein concentrations between 0.1-2.0 mg/mL when using a standard 1 cm pathlength cuvette.