Principal 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 at Xaira, you will play a critical role in the AI-driven discovery and development of protein therapeutics, integrating experimental protein engineering with computational design.

As a Principal Scientist, you will provide scientific and technical leadership from program conception through early discovery and lead optimization. You will partner closely with computational protein designers to guide AI-driven design campaigns and develop experimental strategies to evaluate designed molecules. You will engineer, produce, and characterize 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 demonstrated ability to guide scientific strategy and mentor junior staff. This is a hands-on, lab-based, on-site position with significant program leadership responsibilities.

Responsibilities

Define the scientific strategy for one or more therapeutic programs in partnership with the Disease Biology and Therapeutic Protein Design teams. Contribute to the evaluation of novel targets, define therapeutic hypotheses and target product profiles, and develop integrated, AI-driven drug discovery strategies.

Work closely with computational protein designers to identify relevant structural and biological features of therapeutic targets and incorporate these insights into design campaigns.

Lead binder discovery campaigns, working closely with internal teams to prioritize screening strategies, interpret results, and identify hits.

Collaborate with protein designers to develop and execute strategies to optimize binder affinity, specificity, and developability.

Serve as a scientific lead in cross-functional program meetings, communicating protein engineering strategy and progress to internal stakeholders

Design, produce, purify, and characterize therapeutic proteins, including antibodies, using chromatographic techniques and biophysical and biochemical assays..

Maintain accurate, timely, and complete experimental records in an electronic laboratory notebook (ELN).

Contribute to the preparation of technical reports, regulatory documentation, and scientific presentations.

Ensure compliance with laboratory safety protocols and contribute to laboratory organization and operational efficiency.

Stay current with advances in antibody engineering and protein design, and apply these insights to help shape the team’s scientific direction.

Mentor and develop junior scientific staff, supporting a high-performing, collaborative team.

Oversee CROs supporting outsourced work, ensuring data quality and timely delivery.

Help define and prioritize the Protein Engineering team’s project portfolio in collaboration with leadership.

Qualifications

Ph.D. in a relevant scientific discipline, with a strong foundation in molecular biology, biochemistry, structural biology, or a related field.

At least 6 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 character …