Scientist / Senior Scientist, Peptide Chemistry

About the Role 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. What You’ll Do Lead and scale end-to-end peptide synthesis workflows, including sequence design, resin loading, coupling/deprotection cycles, cleavage, purification, and analytical characterization. Run microwave-assisted solid-phase peptide synthesis, maintain the synthesizer, and troubleshoot failed couplings, low crude purity, side products, cleavage issues, and instrument downtime. Purify and characterize compounds using HPLC, prep HPLC, LC-MS, and related methods; track identity, purity, yield, and batch-level QC before handoff. Design next-round compounds from SAR, in vitro, and in vivo readouts, using potency, stability, and tolerability data to decide what we make next. Who You Are You have 5+ years of hands-on industry experience in organic, medicinal, or peptide chemistry, with strong experimental judgment, deep troubleshooting ability, and a high bar for execution. You’re excited to own synthesis end-to-end: designing compounds, running reactions, purifying and characterizing them, and preparing them for testing with care and urgency. You enjoy solving problems creatively, iterate fast, and keep the science rigorous. You like being close to the biological readout. You want to understand how compounds perform in vitro and in vivo, then use potency and efficacy data to inform the next design cycle. You take responsibility for your work. When an instrument breaks, a synthesis fails, or a handoff is unclear, you troubleshoot and communicate clearly. Pay & Benefits $165,000-$220,000 salary, plus equity options with an implied current value of approximately $50,000-$200,000 before exercise cost, taxes, dilution, and liquidity risk. Compensation will depend on the skills, experience, and scope of impact you bring. If your background, experience, or compensation needs fall outside this range, we are still open to a conversation based on the scope and impact you could bring. $500+ monthly wellness budget for training, supplements, coaching, recovery, or other tools that help you perform at your best. Healthcare: We offer a broad range of medical, dental, and vision coverage options, with Capable covering 100% of the base policy. You will also have access to HSA, FSA, and 401K plans. Healthy dinners with the team are provided daily. We support visa sponsorship where appropriate, including O-1, H-1B, J-1, TN, and other employment-based pathways. Our team is already international, with members from Canada, Pakistan, Germany, Austria, Switzerland, China, India, and the United States. Application Process Our process is fast, transparent, and personal. We care about getting to know the person behind the application. Initial application First phone screen Second phone screen In-person work trial in San Francisco: designed to give both sides a realistic sense of working together. Get to know the founding team! Apply Today Curious but not sure? Apply anyway. It takes 5 minutes, and you do not need to be actively job searching to start a conversation. Some of the best people do not map perfectly to a job description. If this sounds like a place where you could do important work, we would like to hear from you. And if someone exceptional comes to mind, send them our way here. We read every referral carefully, and if your referral joins Capable, we’ll send you a thank-you bonus.