Scientist - Bioconjugation and Purification

Prellis Biologics is advancing next-generation antibody therapeutics by integrating machine learning, scalable biology, and proprietary 3D-printed human lymph node organoids. We are expanding our platform into complex antibody modalities to develop innovative biologic medicines, including programs in obesity and weight loss.

We are seeking a technically rigorous Scientist – Bioconjugation & Purification to lead site-specific conjugation and purification of engineered antibody formats supporting these therapeutic programs.

Role Overview

This Scientist will drive:

• Engineered cysteine (ThioMab-style) site-specific conjugation
• Bromoacetyl–cysteine peptide conjugation to antibodies
• Purification of bispecific antibodies and peptide–antibody fusion proteins

The ideal candidate brings deep expertise in thiol chemistry, selective reduction control, conjugation homogeneity, and chromatographic resolution of complex antibody species.

Key Responsibilities

Site-Specific Bioconjugation

• Design and execute engineered cysteine conjugation workflows while preserving native interchain disulfides.
• Develop and optimize bromoacetyl–cysteine peptide conjugation and related thiol-reactive chemistries.
• Implement controlled reduction strategies to selectively expose engineered thiols.
• Optimize stoichiometry, linker chemistry, and reaction conditions to improve peptide-to-antibody ratios and product uniformity.
• Address heterogeneity drivers including over-reduction, disulfide scrambling, hydrolysis, and aggregation.
• Perform analytical characterization (SEC-HPLC, LC-MS intact/reduced, SDS-PAGE, RP-HPLC).

Purification of Complex Antibody Modalities

• Develop purification workflows for:
  • Monoclonal antibodies
  • Bispecific antibodies
  • Peptide–antibody fusions
  • Conjugated species
• Operate and develop methods on ÄKTA Avant systems.
• Utilize Protein A, IEX, HIC, SEC, and orthogonal chromatographic strategies to resolve unconjugated, partially conjugated, and aggregated species.
• Optimize purity, recovery, and scalability of conjugated products.

Scientific Leadership

• Independently design and execute experiments.
• Contribute to platform development for standardized site-specific conjugation workflows.
• Collaborate cross-functionally with protein engineering and analytical teams.
• Present data clearly and contribute to technical strategy discussions.

Qualifications

Required

• PhD (or MS with significant industry experience) in Biochemistry, Chemical Biology, Bioengineering, or related field.
• Demonstrated expertise in thiol-based, site-specific antibody conjugation, including engineered cysteine platforms.
• Hands-on experience with bromoacetyl–cysteine peptide conjugation chemistry.
• Strong experience developing purification methods on ÄKTA Avant systems.
• Deep understanding of antibody structure, disulfide engineering, and conjugation-driven heterogeneity.

Preferred

• Experience with ADC development or advanced antibody modalities.
• Experience resolving conjugation heterogeneity and improving robustness.
• Exposure to process scale-up or CMC development.

About Prellis Biologics

At Prellis we integrate human biology with machine learning. We aim to revolutionized drug discovery by harnessing the power of human immune system with tightly, integrated machine learning to develop next-generation antibody therapeutics with unparalleled speed, precision and safety. We are committed to empowering our pharmaceutical partners with access to the most promising fully human body candidate rapidly identified from the human immune repertoire, enabling them to bring life-changing treatments to patients faster than ever before.

Prellis Biologics is a pre-IPO biotech located in Berkeley CA with a team-oriented, inclusive, and family-friendly culture. Our growing pipeline target high unmet patient needs across therapeutics including metabolic, inflammation, and oncology disease. Prellis has raised funding from top investors, including Celesta, Khosla Ventures, SOSV, & Avidity Partners.

Application deadline

Prellis does not have an application deadline for this position; we will continue accepting applications until we receive a sufficient number or select a candidate for the position.

Prellis Bio is an equal opportunity employer. All applicants will be considered for employment without attention to race, color, religion, sex, sexual orientation, gender identity, national origin, veteran or disability status.

We believe diversity, equity, and inclusion need to be at the foundation of our culture. We work hard to bring together diverse teams–grounded in a wide range of expertise and life experiences–and work even harder to ensure those teams thrive in inclusive, growth-oriented environments supported by equitable company and team practices. All candidates can expect equitable treatment, respect, and fairness throughout the interview process.