The first enzymatic processes developed at an industrial scale used one enzyme to accomplish one reaction. Over the years, more complex reactions have been conceptualized, involving multiple enzymes working sequentially or in concert to achieve a multi-step reaction.
The need for multiple enzyme reactors is a burden many companies do not relish, and so enzyme co-immobilization has come into favor. This simple but elegant technique increases the efficiency of multi-step enzymatic processes because several enzymes immobilized together on a single carrier can act simultaneously in a one-pot reaction.
Co-immobilization of cascades of enzymes has emerged as a key technology in the biocatalysis industry. This article discusses the benefits and challenges of this technology in the current industry.
What is Co-Immobilization?
Co-immobilization of enzymes refers to the simultaneous attachment of multiple enzymes onto a solid support, allowing for sequential catalytic reactions in a controlled environment. Because they are located on the same surface near each other carrier-bound enzyme cascades reduce mass transfer limitations.
In other words, a substrate molecule does not need to float a long distance before it encounters the next enzyme. Instead, a molecule transformed by one enzyme may be transformed again by the next enzyme as it diffuses out of the same channel. Thus, co-immobilization facilitates rapid substrate conversions.
This rapid conversion is particularly important when the molecular intermediates of a reaction have a short half-life or cause damage to the equipment if they build up.
By co-immobilizing enzymes, manufacturers can create optimized biocatalytic systems tailored to complex reaction pathways, ultimately increasing process efficiency.
Advantages of Co-Immobilization in Industrial Applications
Improved enzyme reuse in the industry
A major advantage of carrier-bound enzymes is their reusability. Unlike soluble enzymes, which are often discarded after a single use, co-immobilized enzymes remain active over multiple reaction cycles, significantly reducing production costs. This enhances enzyme reuse in the industry, making it a sustainable alternative to conventional enzymatic methods.
Increased Stability and Robustness
Industrial environments expose enzymes to varying temperatures, pH levels, and solvents. By leveraging advanced enzyme stabilization methods, industries can ensure that enzyme activity remains intact despite challenging conditions. Co-immobilization further stabilizes the catalytic process, reducing enzyme denaturation and degradation.
Scalability and Process Optimization
As industries focus on industrial enzyme process development, co-immobilization of enzymes presents a scalable and efficient solution for multi-step reactions. The ability to fine-tune enzyme ratios and carrier properties enables precise control over reaction kinetics, enhancing product yield and purity.
Co-Factor Recycling
Many enzymes use a second substrate in their reactions. For example, NAD+ accepts electrons in oxidoreductase enzyme reactions, and Coenzyme A is an acyl group carrier for many cell reactions. These cofactors are expensive and are used up by the action of a single enzyme.
Without a second enzyme to regenerate the cofactor these reactions quickly become unsustainable. So co-immobilization has become important for reactions that require cofactors.
Challenges of Co-Immobilization
Co-immobilization of enzymes can be challenging and is not always appropriate. The co-immobilized enzymes must be compatible with the same enzyme carrier and operate in the same pH, temperature, and solvent solution.
Furthermore, if the reactions produce by-products, they cannot interfere with the other enzymes in the co-immobilized pot. Sometimes one enzyme is much less stable than the others despite efforts to stabilize it. This can lead to the early removal of the entire catalyst. If this is the case, separate immobilization may be required.
Fortunately, most enzymes have evolved to work in similar conditions. In cases where they do not, tools are available to increase their compatibility for co-immobilization. Services are also available to test the enzyme mixture with a wide range of carriers and enzyme immobilization methods.
Enzyme engineering can also be applied to the enzyme molecules themselves to make them compatible with desired pH, temperature, or solvents. Thus, the likelihood of applying enzymes in a single pot is usually very high
Wrapping It Up!
Enzyme immobilization increases the longevity of single enzymes and co-immobilized enzymes. While certain enzymes that work in extreme conditions will always need to be separated into their reactors, most enzymes are compatible with one-pot cascade reactions. This opens up the possibility of complex industrial reactions mimicking those in plants and animals. The many useful molecules accessible this way can be manufactured more simply with less waste, making co-immobilization a crucial technology for the future of biocatalysis.