Protparam

ProtParam - C++ Implementation

A lightweight C++ implementation of the ExPASy ProtParam web tool for analyzing protein sequences. This project calculates several important physicochemical properties of proteins using only their amino acid sequence.

Overview

ProtParam is a popular bioinformatics tool used to estimate various biochemical properties of proteins. This project recreates some of its core functionalities in C++, allowing offline analysis without requiring access to the ExPASy web server.

Features

• Molecular Weight calculation
• Amino Acid Composition
• Count of Acidic and Basic Amino Acids
• Theoretical Isoelectric Point (pI) (simplified implementation)
• Extinction Coefficient estimation
• Fast execution with minimal dependencies
• Console-based interface

Implemented Properties

Property	Status
Molecular Weight	✅
Amino Acid Composition	✅
Acidic/Basic Residue Count	✅
Theoretical pI	✅ (Simplified)
Extinction Coefficient	✅
Instability Index	❌
Aliphatic Index	❌
GRAVY	❌
Estimated Half-life	❌

Project Structure

Protparam-project/
│
├── main.cpp          # Main program
├── Protparam.cpp     # Property calculation functions
└── README.md

Requirements

• C++11 or newer
• GCC / Clang / MSVC

Compilation

Using g++:

g++ main.cpp Protparam.cpp -o protparam

or

g++ *.cpp -o protparam

Usage

Run the executable:

./protparam

Example input:

Enter the protein sequence:
MKWVTFISLLFLFSSAYSRGVFRRDTHKSEIAHRFKDLGE

Example output:

Molecular Weight: 5123.54 Da

Amino Acid Composition
A: 2
D: 1
F: 5
...

Number of acidic amino acids: 3
Number of basic amino acids: 8

Theoretical pI: 8.67

Extinction Coefficient: 12480

Algorithms Used

• Amino acid molecular weight lookup table
• Frequency counting using std::unordered_map
• Simplified pKa-based pI estimation
• Extinction coefficient calculation based on:
  • Tryptophan (W)
  • Tyrosine (Y)
  • Cysteine (C)

Limitations

This project is intended for educational and learning purposes.

Current limitations include:

• Simplified pI calculation
• No support for FASTA files
• No batch sequence processing
• Missing Instability Index
• Missing Aliphatic Index
• Missing GRAVY calculation
• No graphical interface

Future Work

• Add FASTA file support
• Implement the complete ProtParam algorithm
• Add Instability Index
• Add Aliphatic Index
• Add GRAVY calculation
• Improve theoretical pI accuracy
• Export results to CSV
• Unit testing
• CMake support

Disclaimer

This project is an independent implementation inspired by the ExPASy ProtParam web application. It is intended for educational and research purposes only and is not affiliated with or endorsed by ExPASy.

Author

Praveen Gautam

GitHub: https://github.com/Praveengautam759

License

This project is released under the MIT License.