(Senior / Principal) Scientist, Peptide Chemistry

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. 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. Ideal Qualifications 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. Pay & Benefits In addition to the posted salary range, we offer generous equity options. 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. Equal Opportunity Capable is an Equal Opportunity Employer; employment with Capable is governed on the basis of merit, competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.