1. What is Molecular Weight in kDa?

The kilodalton (kDa) is a unit of molecular weight equal to 1000 daltons (Da). It's commonly used to express the molecular mass of proteins and other large molecules in biochemistry.

2. How Does the Calculator Work?

The calculator uses the simple conversion formula:

Where:

• \( MW_{Da} \) — Molecular weight in daltons
• 1000 — Conversion factor from Da to kDa

Explanation: Since 1 kDa equals 1000 daltons, dividing the molecular weight in daltons by 1000 converts it to kilodaltons.

3. Importance of Molecular Weight Calculation

Details: Knowing a protein's molecular weight is essential for gel electrophoresis, chromatography, protein purification, and determining molar concentrations.

4. Using the Calculator

Tips: Enter the molecular weight in daltons (Da) and the calculator will automatically convert it to kilodaltons (kDa). The input must be a positive number.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between Da and kDa?
A: 1 kDa equals 1000 Da. kDa is used for larger molecules like proteins, while Da is used for smaller molecules.

Q2: How do I find my protein's molecular weight in Da?
A: You can calculate it by summing the atomic weights of all atoms in the protein or use protein sequence analysis tools.

Q3: What is a typical protein molecular weight?
A: Most proteins range from a few kDa to several hundred kDa. For example, insulin is about 5.8 kDa while hemoglobin is about 64.5 kDa.

Q4: Why use kDa instead of Da for proteins?
A: Using kDa makes protein molecular weights easier to work with since they're typically in the thousands of daltons.

Q5: Is molecular weight the same as molar mass?
A: Numerically they're the same when expressed in daltons (Da), but molar mass is technically grams per mole while molecular weight is unitless.