Senior Scientist, Protein Engineering

Senior Scientist, Protein Engineering

South San Francisco, California, United States

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.

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, producing, and characterizing proteins and antibodies, with an emphasis on engineering desired functions and evaluating drug-like properties. The ideal candidate will bring deep technical expertise in protein engineering, a strong understanding of antibody formats and develop ability metrics, and a collaborative mindset.

This is a hands-on, on-site position.

• Partner with Disease Biology and Therapeutic Binder Design teams to evaluate new targets, define therapeutic hypotheses and target molecule profiles, and plan and coordinate the execution of drug discovery programs.
• Design and carry out protein engineering efforts, including antibody format optimization and antigen design.
• Express, purify, and characterize tool and therapeutic antibodies and proteins using chromatographic techniques and biophysical/biochemical assays.
• Assess the develop ability profile of therapeutic molecules (e.g., stability, specificity, immunogenicity) by in silico and analytical methods.
• Collaborate with computational protein design, screening, protein science, pharmacology and biology teams to advance programs toward clinical development.
• Collaborate with computational teams and provide clear articulation of biological constraints including immunogenicity and manufacturability.
• Present data at protein engineering group meetings and at cross-functional team meetings.
• Maintain accurate, timely, and well-documented experiment records in ELN.
• Ensure compliance with laboratory safety protocols; contribute to lab organization and operational efficiency.
• Contribute to the preparation of technical reports, regulatory documentation, and scientific presentations.
• Stay current on advancements 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.

• Ph.D. in a relevant scientific discipline, with a strong foundation in molecular biology, biochemistry, structural biology, or a related field.
• Minimum of 4 years of post-academic experience in a biotech or biopharma R&D environment supporting large molecule-based 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 develop ability assessments and stability studies.
• Fluency with protein visualization and structural modeling software (e.g., PyMOL, Alpha Fold).
• Experience with protein/protein interaction assays is preferred.
• Experience interacting with CMC and writing IND reports 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…