Stable Coenzyme Stabilization of Dehydrogenases
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Solution Overview
Problem
Biochemical measuring systems have limited shelf life and require specific environmental conditions for stability, leading to potential incorrect results due to enzyme instability, especially with unstable coenzymes like NAD and NADP, which degrade easily and affect analyte measurement accuracy.
Innovation Solution
Stabilizing enzymes by storing them with a stable coenzyme, such as carbaNAD, which provides long-term stability even at high humidity and elevated temperatures, and using genetically modified glucose dehydrogenase variants with specific mutations for enhanced thermal and hydrolytic stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If native coenzymes (NAD/NADP) are used in biochemical measuring systems, then the enzyme-coenzyme complex can perform catalytic reactions, but the coenzymes degrade rapidly due to base-lability and acid-lability, leading to limited shelf life and measurement inaccuracies
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the coenzyme to create stable analogs. Specifically, the ribose moiety is replaced with isosteric substitutes that have different chemical properties (resistance to base and acid hydrolysis) while maintaining the same spatial arrangement for enzyme binding. This structural parameter change resolves the contradiction by preserving measurement accuracy through maintained enzyme recognition while dramatically extending shelf life through resistance to degradation pathways.
Solution Approach 2:
The patent creates composite molecular structures by combining the stable analog ribose substitute with the original pyridine nucleotide components. The resulting hybrid coenzyme structure integrates the stability of the substituted ribose with the catalytic functionality of the NAD/NADP core structure, achieving both long-term stability and reliable enzymatic activity for accurate measurements.
2Duration of action of stationary object
If environmental controls (cooling, dry storage) are implemented to maintain enzyme stability, then shelf life is extended, but the system requires special storage conditions that may not be maintained by end users, leading to incorrect measurements
Solution Approach 1:
The stable coenzyme analogs are self-stabilizing molecules that do not require external protective measures. Their inherent resistance to base and acid hydrolysis allows them to maintain stability autonomously under normal storage conditions without needing cooling or specialized dry storage environments. This self-service property resolves the contradiction by enabling both extended shelf life and ease of operation, as the coenzymes protect themselves against degradation.
Solution Approach 2:
The patent provides beforehand cushioning by pre-modifying the coenzyme structure to resist degradation before any adverse conditions occur. The stable analogs are designed with built-in protection against hydrolytic degradation pathways, cushioning the system against the harmful effects of humidity, temperature fluctuations, and extended storage without requiring external protective measures during use or storage.
3Reliability
If mediators with low redox potential are used to increase test specificity, then interference is eliminated, but the reaction with the enzyme/coenzyme complex is slowed down or stopped when redox potential falls below the enzyme/coenzyme complex potential
Solution Approach 1:
The patent extracts the need for mediators entirely from the system by using stable coenzyme analogs that can be detected directly. The stable analogs maintain sufficient enzymatic activity and detectability without requiring mediator molecules, thus eliminating the redox potential compatibility constraint. This extraction resolves the contradiction by removing the mediator component that caused the trade-off between specificity and reaction rate.
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
The method achieves long-term enzyme stabilization for several weeks or months, maintaining enzyme activity with reduced degradation, allowing for accurate analyte detection without the need for drying agents or mediators, and can be used in test elements for detecting analytes in various samples.
Implementation Method 1
NAD and NADP are base-labile molecules whose degradation pathways are described in the literature... N.J. Oppenheimer in The Pyridine Nucleotide Coenzymes Academic Press New York, London 1982, eds. J. Everese, B. Anderson, K. You, Chapter 3, pages 56-65. Essentially, when NAD or NADP is broken down, ADP-ribose is formed by cleaving the glycosyl bonds between the ribose and the pyridine unit. The reduced forms NADH and NADPH, on the other hand, are acid-labile: e.g. epimerization is a well-known degradation pathway. In both cases, the instability of NAD/NADP and NADH/NADPH derives from the lability of the glycosyl bond between the ribose and pyridine moieties.
Implementation Method 2
The analytes are converted with the help of an enzyme-coenzyme complex and then quantified. The analyte to be determined is brought into contact with a suitable enzyme and a coenzyme, with the enzyme usually being used in catalytic amounts. The coenzyme is changed by the enzymatic reaction, e.g. oxidized or reduced.
Implementation Method 3
The coenzyme is changed by the enzymatic reaction, e.g. oxidized or reduced. This process can be recorded electrochemically or photometrically directly or by a mediator.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
The present invention relates to a method for stabilizing an enzyme by storing the enzyme in the presence of a stable coenzyme. Furthermore, the present invention relates to an enzyme stabilized using a stable coenzyme and to the use thereof in test elements for detecting analytes.