Many biotechnological techniques used in modern clinical diagnostics, particularly genomics, depend on DNA polymerases, enzymes with the ability to replicate DNA strands.¹ However, many applications require the use of a DNA polymerase that’s been specifically engineered to give it optimal characteristics.¹ Often, standard or wild-type polymerases aren’t enough.¹ Read more to find out how Medix Biochemica solves this challenge.²

The challenge of matching polymerases to assays in diagnostics

Wild-type (naturally occurring) polymerase families have characteristics that make them better suited for certain types of diagnostic assays.² These characteristics include:¹ 

• thermostability (stability at high temperatures);
• extension rate (the speed at which they synthesize DNA);
• processivity (the ability to catalyze consecutive reactions without releasing their substrate);
• fidelity (how accurately they can replicate a DNA template);
• specificity (ability to accurately recognize and bind to the correct nucleotide during DNA synthesis);
  damage bypass (ability for replication to continue past DNA lesions that would normally stall the replication machinery);
• inhibitor resistance (ability to maintain their function in the presence of inhibitors that would normally interfere with their activity);
• strand displacement activity (ability to displace downstream DNA rather than degrading it);
• nuclease activity (ability to cleave phosphodiester bonds in nucleic acids); and
• the ability to incorporate modified nucleotides and replicate templates with altered backbones.

But every assay requires a different set of characteristics for optimization and this is a difficult challenge to meet using naturally occurring polymerases. An off-the-shelf standard polymerase may fit many tests adequately, but rarely fits any test perfectly, and it can therefore limit the application of molecular techniques.²

Our solution: Assay-specific polymerase variants 

New diagnostic platforms often push traditional polymerases beyond their naturally evolved capabilities, but, using our understanding of the performance characteristics of these enzymes, Medix Biochemica is able to engineer and customize them to unlock new solutions.²

Polymerase engineering expertise 

myPOLS Biotec is proud to be a part of Medix Biochemica. Founded in 2014, it started as a project by scientists from the University of Konstanz, Germany. Together, the whole myPOLS Biotec team has nearly 50 years’ experience in DNA polymerase research and development.³ 

myPOLS Biotec’s vision has always been to work together with polymerase end users to tailor every aspect of the enzymes and master mixes, creating truly custom polymerases and unlocking novel capabilities that would otherwise be limited in naturally occurring polymerases.³

How Medix Biochemica optimizes polymerases

• We have a deep understanding of assay design and diagnostic system requirements.²
• We have a unique library of polymerase variants engineered to support specific assay conditions.²
• We have the ability to screen and select the ideal enzyme, or create customized solutions, tailored to the assay's performance needs.²

Optimizing buffers for assays

It’s not only the polymerase (or polymerase variant) that makes up these tailored solutions; the buffer also plays a key role. The buffer maintains a stable pH and contains components that can support or improve the polymerase’s performance, especially when it comes to inhibitor tolerance and stabilizing polymerase activity. At times, the buffer may even have a larger impact on assay performance than the polymerase itself.⁴ 

Medix Biochemica has expertise in optimizing these buffers.² 

The combination of an engineered polymerase and an optimized buffer is particularly powerful in molecular diagnostic applications. With a buffer and enzyme tuned precisely to your assay, you can expect better stability, efficiency, accuracy and robustness.²

Where assay-specific polymerases make the difference 

Here are some real-world applications of Medix Biochemica’s engineered polymerases:

• They are used for precision molecular diagnostics workflows that demand high specificity – such as detecting antimicrobial resistance genes or oncogenic single nucleotide variants against a background of wild-type DNA. With enhanced mismatch discrimination, they enable simple, reliable yes/no results using standard qPCR, eliminating the need for confirmatory sequencing.⁴
  
  
• They enable direct amplification from challenging or inhibitor-rich sample types, enabling reliable detection of low-level targets without the need for prior nucleic acid extraction.⁴
  
  
• Thanks to polymerase engineering, the following improvements have advanced the field of infectious disease testing:⁵
  • More sensitive detection of pathogens (i.e. lower limit of detection).
  • Enhanced specificity to reduce likelihood of false positives.
  • More efficient polymerases to speed up the polymerase chain reaction (PCR) process. This is crucial in infectious disease diagnostics where rapid results can lead to quicker treatment decisions and implementation of containment measures.
  • Reliable results obtained using crude samples without the extraction step.
  • Engineered polymerases can now recognize a wider range of sequences or function under varying conditions.
  • Tests have been developed to detect a broader spectrum of pathogens, including emerging or mutating infectious agents.
    
    
• Medix Biochemica’s Volcano® product line includes a Taq polymerase that has been engineered to have reverse transcriptase activity.²
  • This allows for a thermostable reverse transcription and amplification step to be carried out simultaneously using only one enzyme, leading to faster, simpler workflows.⁴
  • The thermostable reverse transcriptase activity enhances the breakdown of secondary RNA structures, leading to more complete and accurate cDNA synthesis.^2,4
  • True ‘Lyse & Detect’ protocols can now be followed, whereby viral particles are lysed, RNA is synthesized into complementary DNA (cDNA) and this cDNA is amplified for analysis – all in one tube, following one protocol.²

Whether you're optimizing a cutting-edge assay or expanding an existing platform, our custom engineered polymerases therefore give you the competitive edge.²

The future of enzyme design: Smarter, customized and performance driven

Innovation in enzyme engineering is gathering momentum and enzyme engineering and diagnostics are taking center stage at thought-leadership events like ESCMID Global 20257 and the Enzyme Engineering XXVIII conference.⁸

There are three main methods of enzyme or polymerase engineering, each with their own advantages:

Directed evolution^6,9

This strategy can be achieved by two major methods: 

1. DNA shuffling: Recombining fragments or mutations from related genes to generate novel variants.
2. Random mutagenesis: Introducing random mutations into a gene to create a diverse library of enzyme variants.

Followed by the library screening method or selection process: Screening large libraries of mutated genes to identify variants with improved or novel properties.⁹

The advantage of the directed evolution method is that it’s not necessary to know detailed information about the relevant amino acid sequence and function. However, this method results in a huge number of mutations, which may then need several rounds of screening. Directed evolution can therefore be time-consuming and labor-intensive.⁹

Rational protein design⁶

Precise design, based on detailed information about the protein, is used to mutate amino acid sequences and then change the specific amino acids through substitution, insertions or deletions. Rational design has a high success rate, but it relies on a deep understanding of the functional relationship of the protein structure.

Semirational design⁶

Semirational design combines the advantages of directed evolution and rational protein design, creating smaller libraries based on the known information about a protein. 

The combinatorial active-site saturation test (CAST) is a widely used technology for semirational design. The test uses the information derived from structural data to identify the specific amino acids and then mutate them. 

Semirational design can avoid the disadvantages of rational protein design by adding the rational element to directed evolution, limiting the library to specified sites.

Looking to the future: Machine learning in enzyme engineering¹⁰

The application of machine learning (ML) has helped to overcome most of the limitations encountered in the three approaches described above. However, the untapped potential of ML in this field needs to be explored further. Challenges include: 

• lack of uniform, reliable and high-quality data sets for training and validation;
• traditional imbalances and biases in data;
• the inherent multidisciplinary nature of the approach; and
• complexities involved in interpreting and comparing the results of predictors. 

These issues are gaining more attention as the field of enzyme engineering continues to grow. 

Advanced experimental techniques are also becoming more widely used, e.g.: 

• next-generation sequencing;
• high-throughput screening;
• deep mutational scanning; and
• microfluidics.

These techniques enable the collection of larger data quantities with better quality and consistency. With the accumulation of this additional data, sophisticated ML techniques such as deep learning are becoming more prevalent.

Partner with experts who understand your unique assay requirements

Ultimately, tailoring molecular diagnostic reagents to the assay design – rather than forcing the assay to fit the reagents – is the path forward for superior and sustainable diagnostics.² Medix Biochemica brings you unmatched expertise in engineering these reagents for molecular diagnostic success. 

Engage with us early in the assay development process to optimize your platform with the right-fit enzymes.²

References:

1. Aschenbrenner J, Marx A. DNA polymerases and biotechnological applications. Current Opinion in Biotechnology. 2017;48:187-195. doi:10.1016/j.copbio.2017.04.005.
2. Expert opinion. Anthony Austin. Global Marketing Manager, Medix Biochemica. May 2025.
3. About myPOLS Biotec. myPOLS Biotec. Accessed May 25, 2025. https://mypols.de/pages/about-mypols-biotec.
4. Expert opinion. Rob Thompson. Medix Biochemica. June 2025.
5. Novel engineered polymerases for the detection of infectious disease. Medix Biochemica webinar. 27 March 2024. https://articles.medixbiochemica.com/medixmdx-engineered-polymerases-webinar.
6. Xin F, Dong W, Dai Z, et al. Chapter 9 - Biosynthetic technology and bioprocess engineering. In: Singh SP, Pandey A, Du G, et al., eds. Current developments in biotechnology and bioengineering. Elsevier; 2019:207-232. doi:10.1016/B978-0-444-64085-7.00009-5.
7. Final programme. ESCMID. Accessed May 26, 2025. https://www.escmid.org/congress-events/escmid-global/programme/final-programme/.
8. Enzyme engineering XXVIII. Accessed May 26, 2025. https://engconf.us/conferences/biotechnology/enzyme-engineering-xxviii/.
9. Expert opinion. Ramon Kranaster. Chief Executive Officer, myPOLS Biotec. June 2025.
10. Ndochinwa OG, Wang QY, Amadi OC, et al. Current status and emerging frontiers in enzyme engineering: An industrial perspective. Heliyon. 2024;10(11):e32673. doi:10.1016/j.heliyon.2024.e32673.