Scientist I, Protein Production

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.

The Role
We are seeking a highly motivated and versatile Scientist I to join our Design Hypothesis Testing team. In this role, you will drive the end-to-end process of recombinant protein production — from construct design and molecular cloning through expression, purification, and biophysical characterization. Your work will directly support discovery programs by delivering high-quality protein reagents and generating quantitative insights into molecular interactions.
You will collaborate closely with cross-functional teams, including AI scientists, biologists, and assay developers, to optimize protein workflows, troubleshoot production challenges, and develop scalable, high-throughput systems. This is an opportunity to build integrated expertise across molecular biology, protein biochemistry, and biophysical analysis within a dynamic, interdisciplinary environment.

Responsibilities

• Design and cloning: Design and generate expression constructs (gene synthesis, codon optimization, vector cloning, mutagenesis) to support protein engineering and reagent generation.
• Expression: Express recombinant proteins in multiple systems (E. coli, mammalian, cell-free, etc), optimizing yield and solubility.
• Purification: Purify proteins using chromatographic methods (affinity, ion exchange, size exclusion, etc.) and ensure reproducibility, purity, and stability.
• Protein characterization: Assess protein quality (SDS-PAGE, aSEC, etc), binding properties (BLI, ELISA, etc), and developability properties (ELISA, HIC, etc)
• Biophysical analysis: Design and execute binding and kinetic studies using BLI (Octet/Gator) and/or SPR (Biacore). Analyze sensorgrams, fit binding models, and determine kinetic constants (kon, koff, KD).
• Optimization and troubleshooting: Identify and address challenges related to expression, aggregation, or stability, and implement optimization strategies.
• High-throughput support: Contribute to automation or parallelized expression/purification workflows to enable rapid protein generation.
• Collaboration and documentation: Maintain rigorous electronic lab notebook records, manage reagent inventory, communicate results clearly to cross-functional teams, and contribute to SOP development and continuous workflow improvements.

Qualifications

Required

• Ph.D. in Biochemistry, Molecular Biology, Structural Biology, Protein Engineering, or a related discipline with 0–2 years of postdoctoral or industry experience; or
   B.S./B.A. in a relevant field with 8–10 years of hands-on laboratory experience in protein expression and purification.
• Demonstrated expertise in recombinant protein expression and purification across multiple host systems.
• Expertise with BLI (Octet/Gator) or SPR (Biacore) instrumentation, data analysis, and assay optimization.
• Proficiency in molecular cloning (PCR, Gibson, Golden Gate, mutagenesis) and expression construct design.
• Strong problem-solving skills and ability to troubleshoot independently across molecular and biophysical workflows.
• Excellent organization, record-keeping (ELN), and communication skills.
• Comfortable managing multiple projects in a collaborative, fast-paced research environment.

Preferred

• Familiarity with automation or high-throughput expression/purification pipelines.
• Hands-on experience with chromatography systems (e.g., ÄKTA) and analytical methods (HPLC, MS).
• Understanding of protein stability, aggregation, and formulation principles.

Compensation

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 $110,000 - $138,000 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.