Senior Scientist, Protein Engineering

About Xaira Therapeutics Xaira is an innovative biotech startup focused on leveraging AI to transform drug discovery and development. The company is leading the development of generative AI models to design protein and antibody therapeutics, enabling the creation of medicines against historically hard-to-drug molecular targets. It is also developing foundation models for biology and disease to enable better target elucidation and patient stratification. Collectively, these technologies aim to continually enable the identification of novel therapies and to improve success in drug development. Xaira is headquartered in the San Francisco Bay Area, Seattle, and London. About the Role As a member of the Protein Engineering team, you will play a critical role in the discovery and development of next-generation protein therapeutics. You will be responsible for designing, engineering, producing, and characterizing therapeutic proteins and antibodies, with an emphasis on optimizing functional properties and developability. The ideal candidate will bring deep technical expertise in protein engineering, a strong understanding of antibody formats and developability metrics, and a collaborative mindset. This is a hands-on, on-site position. Responsibilities Partner with Disease Biology and Therapeutic Protein Design teams to evaluate new targets, define therapeutic hypotheses and target product profiles, and develop integrated drug discovery strategies. Design and execute protein engineering strategies to optimize affinity, specificity, format, and developability. Express, purify, and characterize tool and therapeutic proteins, including antibodies, using chromatographic techniques and biophysical/biochemical assays. Coordinate binder discovery campaigns, working closely with internal teams to prioritize screening strategies, interpret results, and advance lead molecules. Collaborate with screening, pharmacology, biology, and computational protein design teams to integrate experimental data, guide molecule optimization, and advance therapeutic protein programs toward clinical development. Present data at protein engineering and cross-functional team meetings. Maintain accurate, timely, and well-documented experiment records in ELN. Contribute to the preparation of technical reports, regulatory documentation, and scientific presentations. Ensure compliance with laboratory safety protocols; contribute to lab organization and operational efficiency. Stay current with advances in antibody engineering and protein design. Mentor and develop junior scientific staff to foster a high-performing and collaborative team. Manage and oversee CROs for outsourced protein production, assay development, and screening, ensuring data quality and timely delivery. Qualifications Ph.D. in a relevant scientific discipline, with a strong foundation in molecular biology, biochemistry, structural biology, or a related field. 4+ years of industry experience in biotech or biopharma R&D supporting large molecule therapeutic programs. Extensive hands-on experience in protein engineering, including structural and functional characterization of antibodies and proteins using state-of-the-art analytical methods. Deep expertise in antibody formats, production, purification, and characterization. Proficiency in developability assessments and stability studies. Fluency with protein visualization and structural modeling software (e.g., PyMOL, AlphaFold). Experience with protein–protein interaction assays (e.g., SPR, BLI) is preferred. Experience interacting with Process Development teams and contributing to IND-enabling documentation is preferred. Strong organizational, communication, and interpersonal skills. Ability to propose novel scientific approaches and a genuine interest in exploring relevant therapeutic hypotheses. Proactive, self-starter mindset with excellent problem-solving and troubleshooting capabilities. Enthusiasm for working in a fast-paced, collaborative startup environment, with a demonstrated ability to foster cooperation and knowledge sharing across multidisciplinary teams. A strong record of scientific achievement as evidenced by first-author publications in peer-reviewed journals or granted patents. Compensation Annual We offer a competitive compensation and benefits package, seeking to provide an open, flexible, and friendly work environment to empower employees and provide them with a platform to develop their long-term careers. A Summary of Benefits is available for all applicants. We offer a competitive package that includes base salary, bonus, and equity. The base pay range for this position is expected to be $150,000 to $170,000 annually; however, the base pay offered may vary depending on the market, job-related knowledge, skills and capabilities, and experience. Xaira Therapeutics an equal-opportunity employer. We believe that our strength is in our differences. Our goal to build a diverse and inclusive team began on day one, and it will never end. TO ALL RECRUITMENT AGENCIES: Xaira Therapeutics does not accept agency resumes. Please do not forward resumes to our jobs alias or employees. Xaira Therapeutics is not responsible for any fees related to unsolicited resumes.