Protein Hydrodynamic Radius Calculator

The hydrodynamic radius (Rh) of a protein is a critical parameter used in biophysical studies and protein analysis. It gives insights into the size and shape of proteins in solution, which are essential for understanding their behavior and interactions.

Calculation Formula

The empirical formula to estimate the hydrodynamic radius (Rh) in nanometers (nm) is:

\[ Rh (nm) = 0.066 \times MW^{1/3} \times k \]

• MW is the molecular weight in kilodaltons (kDa).
• k is the shape factor, which varies between 0.2 (for highly compact structures) and 1.0 (for highly elongated structures).

Example Calculation

For a protein with a molecular weight of 50 kDa and a shape factor of 0.6:

\[ Rh = 0.066 \times (50)^{1/3} \times 0.6 \approx 1.12 \text{ nm} \]

Importance and Usage Scenarios

The hydrodynamic radius is essential for characterizing proteins in various research fields, including structural biology, biophysics, and drug development. This calculator provides an easy way for scientists to estimate protein sizes based on their molecular weights and structural shapes.

Common FAQs

1. What is the hydrodynamic radius?

   • The hydrodynamic radius is the effective size of a protein as it moves through a solution, accounting for both its shape and hydration.

2. Why is the shape factor important?

   • The shape factor corrects the radius for proteins that deviate from spherical shapes, reflecting their true size more accurately.

3. How does molecular weight influence Rh?

   • Larger molecular weights typically correspond to larger radii, but the relationship is non-linear and depends on the protein's shape.