Codexis, Inc. has secured a major milestone in biotechnology with a newly patented innovation for polynucleotide synthesis. This innovation focuses on the patent titled ‘Engineered terminal deoxynucleotidyl transferase variants’. The patent describes engineered TdT polypeptides designed to facilitate template-independent synthesis using specific blocking groups.

Advancing Genetic Engineering

The patent abstract details the provision of engineered terminal deoxynucleotidyl transferase (TdT) polypeptides useful in template-independent polynucleotide synthesis using a nucleoside triphosphate-3-prime-O-removable blocking group (NTP-3-prime-O-RBG). It also encompasses compositions, methods of utilizing these engineered polypeptides, and the specific polynucleotides encoding the engineered terminal deoxynucleotidyl transferases. These variants represent a leap forward in the ability to construct custom DNA sequences without the limitations of traditional template-reliant methods.

Codexis earned the Swanson Reed Patent of the Month award for April 2026 because this invention addresses a fundamental bottleneck in the synthetic biology industry. For decades, researchers have relied on chemical phosphoramidite synthesis, which is often hindered by toxic byproducts and length limitations. By engineering TdT enzymes to efficiently incorporate modified nucleotides, Codexis has provided a sustainable, high-fidelity alternative that enables the production of longer and more complex DNA strands. This breakthrough is essential for the rapid scaling of genomic research and the manufacturing of therapeutic genetic materials.

The invention is considered outstanding due to the high degree of technical mastery required to modify the active site of the TdT enzyme. Native TdT does not easily accept the bulky blocking groups necessary for controlled, step-wise synthesis. Through advanced protein engineering and directed evolution, Codexis created variants that maintain high catalytic activity while managing these synthetic modifications. This precision allows for the automation of DNA synthesis at a level of efficiency previously thought impossible, making it a cornerstone for future developments in personalized medicine and agricultural biotechnology.

This patent further solidifies its value by offering a platform for decentralized DNA manufacturing. Swanson Reed recognized this achievement because it shifts the paradigm from centralized chemical plants to benchtop enzymatic synthesis. The ability to write DNA with the same ease that we read it is a transformative capability that will accelerate the entire life sciences ecosystem. By providing the tools for rapid, enzymatic polynucleotide construction, Codexis has positioned itself at the forefront of the next generation of biotechnological tools, proving that their innovation is both scientifically rigorous and commercially vital.

R&D Tax Credit Eligibility in the USA

The development of these engineered TdT variants likely qualifies for the Research and Development Tax Credit in the United States by satisfying the IRS four-part test. First, the project addresses Technical Uncertainty regarding whether specific mutations in the TdT sequence would yield the desired catalytic efficiency with modified nucleotides. Second, the company utilized a Process of Experimentation involving the creation of vast mutant libraries and iterative screening protocols to identify the most effective variants. Third, the research is Technological in Nature, as it is rooted in the biological sciences and genomic engineering. Finally, the work serves a Permissible Purpose by aiming to create a new and improved functional business component in the form of a proprietary enzyme synthesis kit.

Practical Applications for R&D Tax Credits

• The systematic evaluation of amino acid substitutions within the TdT enzyme structure to improve its binding affinity for 3-prime-O-removable blocking groups.
• Development and refinement of high-throughput screening assays used to measure the incorporation rate of modified nucleoside triphosphates during the enzymatic synthesis process.
• Design and testing of novel chemical formulations for the deblocking step to ensure that the removal of the RBG does not degrade the newly synthesized polynucleotide chain.