Enzymatic DNA Synthesis via pH Control
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Solution Overview
Problem
Current DNA synthesis methods using phosphoramidite precursors in organic solvents are inefficient, error-prone, and costly, limiting the length and accuracy of synthesized DNA strands, and are not suitable for high-speed or cost-effective production.
Innovation Solution
The use of an electric current to alter the pH in a reaction zone, activating an enzyme like terminal deoxynucleotidyl transferase (TdT) to add nucleotides to a growing DNA sequence, enabling enzymatic synthesis of longer and more accurate DNA sequences, and allowing for parallel synthesis of multiple sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical synthesis methods using phosphoramidite precursors are used, then DNA can be synthesized, but the synthesis speed is slow (10 minutes per addition step) and cost is high
Solution Approach 1:
The patent replaces chemical synthesis mechanisms with enzymatic synthesis using terminal deoxynucleotidyl transferase (TdT). The enzyme catalyzes nucleotide addition at the 3' end of DNA strands, enabling faster synthesis rates compared to chemical phosphoramidite methods. The enzymatic reaction proceeds without the complex chemical activation steps required by traditional methods, achieving synthesis speeds of several nucleotides per second.
Solution Approach 2:
The patent utilizes pH as a controllable parameter to regulate TdT enzyme activity. By adjusting pH conditions, the enzyme can be activated or deactivated to control nucleotide addition. This parameter control enables precise regulation of the synthesis process, allowing rapid nucleotide incorporation when activated and preventing unwanted reactions when deactivated, thereby improving overall synthesis efficiency.
2Reliability
If chemical synthesis methods are used, then DNA can be produced, but error rate is high (approximately 1% errors)
Solution Approach 1:
The patent replaces error-prone chemical synthesis with high-fidelity enzymatic synthesis. TdT enzyme incorporates nucleotides with high accuracy through its catalytic mechanism, which includes proofreading capabilities and specific substrate recognition. This enzymatic approach reduces error rates significantly compared to chemical phosphoramidite methods, achieving synthesis accuracy suitable for long DNA strand production.
Solution Approach 2:
The TdT enzyme performs self-correction and quality control during nucleotide incorporation. The enzyme's active site geometry and catalytic mechanism inherently prevent mismatched nucleotide incorporation, providing built-in error prevention without requiring external correction steps. This self-correcting capability significantly reduces synthesis errors compared to chemical methods.
3Length of moving object
If chemical synthesis methods are used, then DNA can be synthesized, but DNA strand length is limited (cannot synthesize strands longer than ~200 bases)
Solution Approach 1:
The patent replaces chemical synthesis with enzymatic synthesis using TdT, which is capable of extending DNA strands to much greater lengths. The enzyme maintains catalytic activity and fidelity over extended synthesis periods, enabling production of DNA strands exceeding 200 bases. The enzymatic mechanism avoids the cumulative error accumulation and reagent degradation issues that limit chemical synthesis length.
Solution Approach 2:
The TdT enzyme maintains continuous catalytic activity for nucleotide addition without the stopping points required by chemical synthesis cycles. The enzymatic reaction can proceed continuously through multiple nucleotide incorporations without requiring intermediate purification or reagent regeneration steps, enabling synthesis of long DNA strands in a single continuous reaction process.
4Ease of manufacture
If chemical synthesis reagents are used, then DNA can be synthesized, but reagent cost is high and DNA damage occurs
Solution Approach 1:
The patent replaces expensive and DNA-damaging chemical reagents with biocompatible enzymatic reagents. TdT and its substrates are designed to work under physiological conditions, eliminating the need for toxic phosphoramidite reagents and strong acids/bases used in chemical synthesis. This substitution reduces both material costs and DNA damage, improving overall manufacturing efficiency and product quality.
Solution Approach 2:
The enzymatic synthesis system operates under mild, physiological conditions that are non-denaturing and non-damaging to DNA. The reaction buffer maintains optimal pH and ionic strength without requiring harsh chemicals, creating a protective environment that preserves DNA integrity throughout the synthesis process. This inert, biocompatible environment prevents reagent-induced DNA damage while enabling efficient synthesis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of cheaper, more accurate, and longer custom DNA sequences, facilitating the use of DNA as a high-speed information storage medium, with potential for parallel synthesis and improved control over nucleotide addition.
Implementation Method 1
an electric current is used to generate a pH within a reaction zone that activates an enzyme
Data Source
AI summary
The present disclosure provides methods of activating an enzyme, such as error prone or template independent polymerase, using electricity to alter pH of a reaction zone and reaction site from an inactivating pH at which the enzyme is inactive to an activating pH at which the enzyme is active to add a nucleotide to an initiator or growing polymer chain. The activating pH can then be changed back to an inactivating pH and the process repeated as many times as desired to produce a target nucleic acid sequence.