Enzymes in crystalline cages, enhanced by salt

Enzyme Power-Up: How Salt Could Be the Secret to Supercharged Biocatalysts

Jordan Keane in Science & Nature September 2025 • 4 min read.

"Unlock the potential of enzymes with a surprising twist: the strategic use of salt to boost their performance and resilience."

Enzymes are nature's catalysts, speeding up reactions with incredible precision. Their applications are vast, from producing pharmaceuticals to cleaning up environmental pollutants. However, enzymes are delicate. They can be difficult to reuse, lose activity quickly, and often come with a hefty price tag, limiting their widespread industrial use.

To overcome these limitations, scientists have been exploring enzyme immobilization – essentially locking enzymes into protective structures. One promising approach involves using metal-organic frameworks (MOFs), particularly zeolitic imidazolate frameworks (ZIFs). ZIFs act like tiny cages, shielding enzymes and enhancing their stability and reusability.

Now, imagine adding a pinch of salt to this equation. Researchers have discovered that the presence of NaCl during enzyme encapsulation in ZIFs can have a surprisingly positive impact. This article delves into how NaCl affects the structure of ZIF-8 and, more importantly, how it can boost the performance and resilience of encapsulated enzymes.

Salt's Surprising Role: From ZIF-8 Morphology to Enzyme Activity

Enzymes in crystalline cages, enhanced by salt

The study investigated the impact of NaCl on the encapsulation of (R)-1-phenylethanol dehydrogenase ((R)-PEDH) within ZIF-8. (R)-PEDH is an enzyme valuable in producing chiral alcohols, essential building blocks in pharmaceuticals and fine chemicals.

Researchers found that the amount of NaCl present during the ZIF-8 formation significantly influenced the resulting structure. Scanning electron microscopy (SEM) revealed that:

Small amounts of NaCl (0.01 M) didn't alter the ZIF-8 structure much.
A concentration of 0.1 M NaCl led to the formation of unique 'flower ball' structures.
Higher concentrations (1 M) resulted in disrupted, lamellar ZIF-8 structures.

Interestingly, while high NaCl concentrations damaged the ZIF-8 structure, a concentration of 0.1 M dramatically improved enzyme activity. (R)-PEDH encapsulated in ZIF-8 with 0.1 M NaCl exhibited 2.5 times higher activity compared to those prepared without NaCl. Further studies revealed that this optimized (R)-PEDH@ZIF-8 also demonstrated enhanced storage stability and resistance to trypsin, an enzyme that degrades proteins.

The Salty Secret to Better Biocatalysts

This research highlights the potential of seemingly simple additives like NaCl to fine-tune enzyme encapsulation within MOFs. By carefully controlling the salt concentration, scientists can influence both the structure of the ZIF-8 and the activity of the encapsulated enzyme.

The flower ball structure formed with 0.1 M NaCl may provide an optimal environment for the enzyme, enhancing its catalytic activity and protecting it from degradation. The enhanced stability and reusability of the (R)-PEDH@ZIF-8 biocatalyst make it a promising candidate for industrial applications.

Further research is needed to fully understand the mechanisms behind NaCl's influence on ZIF-8 structure and enzyme activity. However, this study opens exciting new avenues for developing more robust, efficient, and cost-effective biocatalytic processes.

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This article is based on research published under:

DOI-LINK: 10.1016/j.enzmictec.2018.12.003, Alternate LINK

Title: The Effects Of Nacl On Enzyme Encapsulation By Zeolitic Imidazolate Frameworks-8

Subject: Applied Microbiology and Biotechnology

Journal: Enzyme and Microbial Technology

Publisher: Elsevier BV

Authors: Shujin Pu, Xuan Zhang, Chengli Yang, Sidra Naseer, Xutong Zhang, Jie Ouyang, Dali Li, Junfang Yang

Published: 2019-03-01

Everything You Need To Know

Why are enzymes not more widely used in industrial processes?

Enzymes, nature's catalysts, accelerate reactions with precision and have diverse applications. However, they are delicate, costly, and difficult to reuse, limiting their industrial use. Encapsulation within metal-organic frameworks (MOFs), particularly zeolitic imidazolate frameworks (ZIFs), protects and enhances their stability and reusability, making biocatalysis more effective and sustainable.

How does salt influence enzyme encapsulation?

The presence of NaCl during the encapsulation of (R)-1-phenylethanol dehydrogenase ((R)-PEDH) within ZIF-8 significantly impacts the structure and performance. Specifically, a 0.1 M concentration of NaCl leads to the formation of 'flower ball' structures, boosting the enzyme's activity. However, very high concentrations disrupt the ZIF-8 structure, indicating that optimal salt concentration is key to improved enzyme performance.

What specific benefits were observed when (R)-PEDH was encapsulated in ZIF-8 with NaCl?

Researchers discovered that (R)-PEDH encapsulated in ZIF-8 with 0.1 M NaCl exhibited 2.5 times higher activity compared to those prepared without NaCl. This optimized (R)-PEDH@ZIF-8 also demonstrated enhanced storage stability and resistance to trypsin, an enzyme that degrades proteins, suggesting NaCl not only boosts activity but also protects the enzyme.

Besides NaCl and ZIF-8, what other avenues could be explored to enhance enzyme encapsulation and activity?

While the research primarily focuses on NaCl's effect on (R)-PEDH encapsulation in ZIF-8, it opens avenues for exploring other salts and MOFs. Different salts might offer unique advantages, and exploring various MOFs could lead to even more robust and efficient enzyme encapsulation methods. Further research could investigate the underlying mechanisms of salt-enzyme-MOF interactions, to refine and optimize these processes for a wider range of enzymes and applications.

What are the broader implications of using salt to enhance enzyme activity and stability in industrial biocatalysis?

The implications are significant for industries relying on biocatalysis, such as pharmaceuticals and fine chemicals. By optimizing enzyme encapsulation with additives like NaCl, processes can become more efficient, cost-effective, and sustainable. This could lead to wider adoption of enzymatic reactions in industrial settings, reducing reliance on traditional chemical catalysts and promoting greener manufacturing practices. This is important in the development of chiral alcohols, essential building blocks.