(Senior / Principal) Scientist, Peptide Chemistry

Capable Labs • San Francisco, CA

2d • Onsite

About The Position

We are a vibrant and intensely mission-driven team in San Francisco, comprising members from MIT, Harvard Medical School, Roche, ETH, and Dana-Farber. We value speed and rigor, coupled with excitement, drive, and a strong work ethic. In an early-stage environment, we value people who can bring clarity to open-ended problems, take ownership of the next steps, and follow through with energy. Capable Labs is a place for ambitious, high-integrity people who want to become dramatically better. You will be surrounded by people who care intensely about the work, get close feedback from the people making scientific and company-defining decisions, and have room to own increasingly important problems. We believe excellent work should be met with meaningful reward, ownership, and trust. Responsibility is earned through contribution, not title alone: anyone who demonstrates the judgment, rigor, and follow-through to move important work forward can earn meaningful scope. About the Role You will lead peptide design and synthesis from sequence selection through production, purification, quality control, and biological handoff. You will own difficult chemistry and analytical problems, scale reliable workflows, and use SAR and biological results to help decide what Capable makes next. This is a senior hands-on role with broad technical ownership.

Requirements

• Five or more years of hands-on industry experience in peptide, medicinal, organic, or closely related chemistry.
• Strong experimental judgment and deep troubleshooting ability across synthesis, purification, characterization, and laboratory instrumentation.
• Experience owning chemistry end to end, from compound or sequence design through material ready for biological testing.
• The ability to work close to biological readouts and translate potency, efficacy, stability, exposure, or tolerability data into the next chemistry decision.
• A creative, fast, and rigorous approach to technical problem-solving and workflow improvement.
• The ability to provide technical direction and raise the quality of the team’s work without becoming removed from the bench.

Responsibilities

• Lead and scale end-to-end peptide workflows, including sequence design, resin loading, coupling and deprotection, cleavage, purification, characterization, and final quality control.
• Run, optimize, and maintain microwave-assisted solid-phase peptide synthesis systems.
• Resolve difficult synthetic and analytical issues, including failed couplings, low conversion, low crude purity, side products, cleavage problems, solubility limitations, purification challenges, and instrument downtime.
• Own compound identity, purity, yield, analytical records, and readiness for biological testing.
• Interpret SAR, in vitro, and in vivo readouts—including potency, stability, exposure, tolerability, and efficacy—to design or prioritize next-round compounds.
• Improve synthesis, purification, and handoff workflows so the team can make high-quality compounds faster and more reproducibly.
• Set a high technical bar, communicate risks clearly, and guide other scientists while remaining directly involved in experimental work.

Benefits

• Generous equity options
• $500+ monthly wellness budget for training, supplements, coaching, recovery, or other tools that help you perform at your best.
• Medical, dental, and vision coverage options, with Capable covering 100% of the base policy.
• HSA, FSA, and 401K plans.
• Healthy dinners provided daily.
• Visa sponsorship where appropriate, including O-1, H-1B, J-1, TN, and other employment-based pathways.
• Referral bonus

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed