Protein Weight to Molarity Calculator

Protein Molarity Formula:

\[ M (\mu M) = \frac{C (mg/mL)}{MW (kDa)} \times 1000 \]

Protein Molarity (M):

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1. What is Protein Molarity?

Protein molarity refers to the concentration of a protein solution expressed in micromoles per liter (μM). It's a fundamental measurement in biochemistry that allows researchers to compare protein concentrations on a molecular basis rather than by weight.

2. How Does the Calculator Work?

The calculator uses the protein molarity formula:

\[ M (\mu M) = \frac{C (mg/mL)}{MW (kDa)} \times 1000 \]

Where:

\( M \) — Molarity in micromoles per liter (μM)
\( C \) — Protein concentration in milligrams per milliliter (mg/mL)
\( MW \) — Molecular weight in kilodaltons (kDa)

Explanation: The formula converts weight concentration to molar concentration by accounting for the protein's molecular weight. The 1000 factor converts from mM to μM.

3. Importance of Protein Molarity

Details: Knowing protein molarity is essential for experimental reproducibility, enzyme activity measurements, binding studies, and preparing solutions with specific molecular ratios.

4. Using the Calculator

Tips: Enter protein concentration in mg/mL and molecular weight in kDa. Both values must be positive numbers. For accurate results, use precise measurements of both concentration and molecular weight.

5. Frequently Asked Questions (FAQ)

Q1: Why convert from weight to molar concentration?
A: Molarity allows comparison of molecules on a per-particle basis, which is important for stoichiometric calculations and understanding molecular interactions.

Q2: How do I determine my protein's molecular weight?
A: Use the protein's amino acid sequence with online calculators, or measure it experimentally via mass spectrometry or gel electrophoresis.

Q3: What if my protein is multimeric?
A: Use the molecular weight of the complete multimeric complex, not just the monomer, for accurate molarity calculations.

Q4: Can I use this for nucleic acids?
A: Yes, the same principle applies, though nucleic acids are typically measured in ng/μL rather than mg/mL.

Q5: How precise should my concentration measurement be?
A: For best results, use spectrophotometric (A280) or colorimetric (Bradford, BCA) assays with appropriate standards.