pI Proteína Média
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
This calculator estimates the isoelectric point (pI) of a protein by averaging the pI values of individual amino acids. The pI indicates the pH where the protein has no net charge, essential for processes like purification and electrophoresis. Input an amino acid sequence or select a reference protein. The result is an approximation suitable for scenarios where detailed accuracy isn't required.
The method uses a weighted average of amino acid pI values, considering their acid-base properties. This simplifies complex calculations but may not reflect specific amino acid interactions. A pI around 7 (neutral) is common, though it varies with composition. Ideal for initial biochemical studies or labs with time constraints.
Note: The average method doesn't account for the protein's 3D structure or residue interactions, which affect the actual pI. For higher accuracy, pH-based charge calculations are recommended. Use this tool for quick guidance, not as a substitute for advanced analysis.
Frequently asked questions
Why does the calculation use amino acid averages?
The average simplifies the process by considering individual amino acid properties, but not complex residue interactions.
Is the result accurate for lab applications?
It's a general estimate. For precision, use pH-based charge calculation methods.
Can I use it for unknown protein sequences?
Yes, but accuracy depends on assumed composition. Known sequences yield better results.
What does a pI near 7 indicate?
The protein is neutral in most environments, common in proteins with balanced acidic and basic amino acids.
How to interpret pI variations?
pI above 7 suggests a basic protein; below 7, acidic. Variations help predict solubility and electrophoretic migration.