---
title: 'Principal Scientist, Protein Engineering at Xaira Therapeutics'
canonical: 'https://feeny.ai/job/principal-scientist-protein-engineering-xaira-therapeutics-south-san-francisco-2dwzf5jmc3sv'
type: 'job'
last_seen: '2026-10-19'
---

# Principal Scientist, Protein Engineering at Xaira Therapeutics

- **Company:** Xaira Therapeutics
- **Location:** South San Francisco, CA
- **Posted:** 2026-09-28
- **Last confirmed live:** 2026-10-19
- **Apply:** https://job-boards.greenhouse.io/xairatherapeutics/jobs/5250920007

## Job description

## 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 characterization of antibodies and other proteins using advanced analytical methods.
- Deep expertise in antibody formats, production, purification, and characterization.
- Proficiency in developability assessments and stability studies.
- Proficiency with protein visualization and structure prediction tools, such as PyMOL and AlphaFold.
- Strong organizational, communication, and interpersonal skills.
- Ability to propose novel scientific approaches and a strong interest in exploring relevant therapeutic hypotheses.
- A proactive, self-directed approach, with excellent problem-solving and troubleshooting skills.
- Enthusiasm for working in a fast-paced, collaborative startup environment, with a demonstrated ability to promote cooperation and knowledge sharing across multidisciplinary teams.
- A strong record of scientific achievement, demonstrated by first-author publications in peer-reviewed journals or granted patents.
- Direct experience with structure prediction or machine learning tools for protein design is preferred.
- Experience collaborating with Process Development and supporting IND documentation is nice to have.

## 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 $164,000 to $205,000 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.

## About Xaira Therapeutics

## Company Overview
- **One-liner**: Xaira Therapeutics is an integrated biotechnology company applying artificial intelligence across the entire drug discovery and development process to design next-generation medicines.
- **Entity Type**: Private (Series A)
- **Headquarters**: South San Francisco, California, United States (with offices in Seattle, Washington, and London, UK)
- **Founded**: 2023
- **Founders**: Co-founded and incubated by ARCH Venture Partners and Foresite Labs, with foundational scientific contributions from Nobel Laureate Dr. David Baker (Institute for Protein Design, University of Washington).

## Core Business
- **Primary industry/industries**: Biotechnology, Drug Discovery & Development, Artificial Intelligence
- **Target customers**: B2B (pharmaceutical partners, biotech collaborators) and ultimately patients via its own therapeutic pipeline.
- **Mission or purpose statement**: "Pioneering the transformative artificial intelligence that will help discover and develop the next generation of life-changing medicines." [xaira.com](https://www.xaira.com/)

## Products & Services
- **AI-Powered Drug Discovery Platform**: An end-to-end platform integrating advanced AI research, expansive data generation (functional genomics, proteomics, multi-omics), and robust therapeutic product development to shift drug discovery from an empirical science to a precise engineering discipline. [xaira.com](https://www.xaira.com/our-approach)
- **Computational Protein Design**: Built on foundational work by Nobel Laureate Dr. David Baker, leveraging AI to design entirely new proteins from scratch for previously undruggable targets. [xaira.com](https://www.xaira.com/our-approach)
- **X-Cell (Virtual Cell Model)**: An AI model trained on billions of genomic data points to simulate and understand cellular biology. [xaira.com](https://www.xaira.com/)
- **Therapeutic Pipeline**: A pipeline of differentiated therapeutics across multiple modalities (small molecules, biologics, protein therapeutics) developed through an integrated AI-driven process.

## Market Standing
- **Valuation/Market Cap**: Not publicly disclosed. The company launched in 2023 with a $1 billion Series A financing, one of the largest in biotech history.
- **Key Metric**: Total Funding of $1 billion (Series A, 2023).
- **Notable Investors/Partners**: ARCH Venture Partners (co-founder and lead investor), Foresite Labs (co-founder and incubator), F-Prime Capital, and other top-tier investors. Board includes leaders from ARCH, Foresite, NEA, and Johnson & Johnson. Scientific advisors include Nobel Laureates Carolyn R. Bertozzi and David Baker, and other luminaries. [xaira.com](https://www.xaira.com/our-team)
- **Growth Signals**: Launched in 2023 with a record $1B Series A; rapidly building a world-class team across three global hubs (South San Francisco, Seattle, London); actively hiring across AI, computational biology, protein design, and drug development roles; announced X-Cell, a virtual cell model trained on billions of genomic data points. [xaira.com](https://www.xaira.com/)

## Competitive Advantages
- **Unprecedented Capital & Talent**: Launched with a $1B Series A, enabling aggressive hiring of top-tier AI and biology talent and long-term investment in infrastructure.
- **End-to-End AI Integration**: Uniquely positioned to apply AI across the entire drug discovery and development lifecycle, from target identification to clinical development, creating a powerful data flywheel.
- **World-Class Scientific Foundation**: Built on foundational AI protein design work from Nobel Laureate David Baker's lab, with a board and advisory board including multiple Nobel Laureates, former FDA commissioners, and industry leaders from Genentech, Johnson & Johnson, and top venture firms. [xaira.com](https://www.xaira.com/our-team)
- **Massive Data Generation**: Investing heavily in functional genomics and proteomics to generate proprietary, multi-dimensional datasets that fuel AI model development, creating a defensible data moat.

## Strategic Focus
- **End-to-End AI Integration**: Building predictive and agentic AI models across the complete drug discovery and development spectrum to increase probability of success, reduce timelines, and lower costs. [xaira.com](https://www.xaira.com/our-approach)
- **Data as a Core Asset**: Generating and integrating massive, multi-dimensional biological datasets (from molecular to human scales) to train and improve AI models continuously.
- **Pipeline Development**: Advancing a pipeline of differentiated therapeutics across multiple modalities (small molecules, biologics, protein therapeutics).
- **Talent Acquisition**: Aggressively hiring across AI research, engineering, computational biology, protein design, and drug development to build a world-class, interdisciplinary team.

## Why Work Here
- **Mission-Driven**: Opportunity to work at the forefront of AI and biology to fundamentally transform how medicines are discovered and developed, with the potential to impact millions of patients.
- **World-Class Team & Mentorship**: Work alongside and learn from Nobel Laureates, top AI researchers, and experienced drug developers from leading pharma and biotech companies. [xaira.com](https://www.xaira.com/our-team)
- **Interdisciplinary Culture**: A unique blend of AI/ML engineers, protein designers, computational biologists, and drug hunters all working together in a highly collaborative environment.
- **Global Hubs & Flexibility**: Offices in South San Francisco, Seattle, and London, offering multiple locations for talent.
- **Generous Resources**: Backed by a $1B Series A, providing the resources to pursue ambitious, long-term research without short-term funding pressure.
- **Job Scam Awareness**: The company has issued a warning about fraudulent job offers; all legitimate recruitment is conducted through official channels (Greenhouse) and never via Google Chat or requests for payment. [xaira.com](https://www.xaira.com/work-with-us)

## Sources
1. [xaira.com](https://www.xaira.com/)
2. [xaira.com](https://www.xaira.com/our-approach)
3. [xaira.com](https://www.xaira.com/our-team)
4. [xaira.com](https://www.xaira.com/work-with-us)
5. [greenhouse.io](https://job-boards.greenhouse.io/xairatherapeutics)

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