peptidegym

Gymnasium-Compatible RL Environments for Therapeutic Peptide Design

PeptideGym provides the first Gymnasium-compatible reinforcement learning environments for therapeutic peptide design. It models peptide construction as a sequential decision process — an RL agent builds peptide sequences residue-by-residue, receiving rewards from pluggable biophysical property predictors. PeptideGym enables researchers to benchmark any Gymnasium-compatible RL algorithm (PPO, DQN, SAC via Stable Baselines3, CleanRL, or RLlib) on peptide design without writing custom training loops.

Three environment families cover distinct therapeutic peptide classes:

• Antimicrobial peptides (AMPs) — cationic, amphipathic sequences that disrupt microbial membranes
• Cyclic peptides — macrocyclic binders with enhanced stability and oral bioavailability
• Vaccine epitopes — short peptides optimized for MHC-I binding and T-cell recognition

Installation

pip install peptidegym              # Core (numpy, gymnasium)
pip install peptidegym[train]       # + SB3, PyTorch for RL training
pip install peptidegym[all]         # Everything

Development install:

git clone https://github.com/HassDhia/peptidegym.git
cd peptidegym
pip install -e ".[all]"

Quick Start

import gymnasium as gym
import peptidegym

env = gym.make("PeptideGym/AMP-v0")
obs, info = env.reset(seed=42)
for _ in range(100):
    action = env.action_space.sample()
    obs, reward, terminated, truncated, info = env.step(action)
    if terminated or truncated:
        print(f"Designed peptide: {info['sequence']} (reward: {reward:.3f})")
        obs, info = env.reset()
env.close()

Train a PPO Agent

from stable_baselines3 import PPO
import gymnasium as gym
import peptidegym

env = gym.make("PeptideGym/AMP-v0")
model = PPO("MlpPolicy", env, verbose=1)
model.learn(total_timesteps=90_000)

# Evaluate
obs, _ = env.reset()
done = False
while not done:
    action, _ = model.predict(obs, deterministic=True)
    obs, reward, terminated, truncated, info = env.step(action)
    done = terminated or truncated
print(f"Designed AMP: {info['sequence']}, Activity: {info.get('activity_score', 'N/A')}")

Environments

Each environment is available in three difficulty tiers (e.g., PeptideGym/AMP-Easy-v0, PeptideGym/AMP-Hard-v0) for a total of 9 benchmark configurations.

Architecture

┌─────────────────────────────────────────────────────┐
│                   RL Agent (PPO)                     │
│              via Stable Baselines3                   │
└────────────────────┬────────────────────────────────┘
                     │ action (amino acid or special)
                     ▼
┌─────────────────────────────────────────────────────┐
│              PeptideGym Environment                  │
│  ┌───────────┐  ┌──────────────┐  ┌───────────┐    │
│  │  AMP-v0   │  │CyclicPep-v0  │  │ Epitope-v0│    │
│  └─────┬─────┘  └──────┬───────┘  └─────┬─────┘    │
│        └───────────────┬┘───────────────┘            │
│                        ▼                             │
│            Pluggable RewardBackend                   │
│  ┌──────────────┐  ┌──────────────┐  ┌───────────┐ │
│  │  Heuristic   │  │   AMPlify    │  │ NetMHCpan │ │
│  │  (default)   │  │  (optional)  │  │ (optional)│ │
│  └──────────────┘  └──────────────┘  └───────────┘ │
└─────────────────────────────────────────────────────┘

All environments share the Gymnasium API (reset(), step(), observation_space, action_space). Default heuristic reward backends require no external dependencies. Optional backends (AMPlify, NetMHCpan, MHCflurry) can be swapped in for research-grade reward signals.

Paper

The accompanying paper is available at:

• PDF (GitHub)

Citation

If you use peptidegym in your research, please cite:

@software{dhia2026peptidegym,
  author = {Dhia, Hass},
  title = {PeptideGym: Gymnasium-Compatible Reinforcement Learning Environments for Therapeutic Peptide Design},
  year = {2026},
  publisher = {Smart Technology Investments Research Institute},
  url = {https://github.com/HassDhia/peptidegym}
}

License

MIT License. See LICENSE for details.

Contact

Hass Dhia -- Smart Technology Investments Research Institute

• Email: partners@smarttechinvest.com
• Web: smarttechinvest.com/research