Structural Biology Calculators
Structural biology calculators assist researchers in analyzing protein geometry, folding, and 3D organization. These tools simplify quantitative estimations such as secondary structure fractions, solvent exposure, compactness, and molecular size.
Use these interactive calculators to explore protein hydrophobicity, disulfide bonding potential, salt bridge formation, and Ramachandran plot statistics. Each formula applies standard biophysical approximations to help interpret structural models and sequences effectively.
⚠ Disclaimer:
This calculator provides results based on standard formulas and simplified assumptions.
It is intended for educational purposes only and should not be used for professional,
medical, industrial, or experimental applications without expert verification.
1. Secondary structure fractions (α-helix / β-sheet / coil)
Result will appear here.
Output shows percent of helix, sheet and coil.
2. Solvent Accessible Surface Area (SASA) — estimator
Result will appear here.
Empirical estimate: SASA ≈ 6 × (MW in Da)^(2/3) — rough approximation.
3. Protein molecular radius (est.)
Result will appear here.
Rule-of-thumb: radius (nm) ≈ 0.066 × mass^(1/3) (Da) — approximates hydrodynamic size.
4. Radius of gyration (Rg) — compactness
Result will appear here.
Approx: Rg (nm) ≈ 0.22 × N^0.6 (typical for folded proteins).
5. Salt bridge count (est.)
Result will appear here.
Rough estimator: possible salt bridges ≈ min(acidic, basic) (upper bound).
6. Hydrophobicity index (Kyte-Doolittle average)
Result will appear here.
Non-letter characters will be ignored. Uses Kyte-Doolittle scale.
7. Disulfide bond likelihood (from # Cys)
Result will appear here.
Possible Cys–Cys pairs = nC2 = n*(n−1)/2 (pairs). Real bonds ≤ pairs; depends on folding.
8. Ramachandran favored residue percentage
Result will appear here.
Output = (favored / total) × 100%.