Heat-Labile Hyperactive DNase for DNA Degradation
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Solution Overview
Problem
Current DNases are inadequate for efficiently degrading DNA in samples without interfering with RNA or protein detection, particularly in reverse transcription reactions, due to their stability and activity limitations.
Innovation Solution
Development of heat-labile, hyperactive DNases with specific amino acid sequences and fusion with heterologous non-specific DNA binding domains, which can be used in combination with topoisomerases to enhance DNA degradation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DNases are used to degrade DNA, then DNA removal is achieved, but the DNases remain stable and active, requiring separate inactivation or removal steps that complicate the process
Solution Approach 1:
The patent introduces heat-labile mutations that change the thermal stability parameter of DNase I, allowing the enzyme to be inactivated by heating at 50-65°C without affecting RNA or protein. This parameter change enables automatic inactivation after DNA degradation, eliminating separate inactivation steps and reducing process complexity.
Solution Approach 2:
The patent performs DNA degradation as a preliminary action before reverse transcription, using heat-labile DNase I that is automatically inactivated by the subsequent heating step required for reverse transcription initiation. This preliminary action integrated with the existing workflow eliminates the need for separate DNase inactivation or removal steps.
2Productivity
If DNase activity is increased to improve DNA degradation, then degradation efficiency improves, but interference with RNA or protein detection may increase
Solution Approach 1:
The patent creates heat-labile variants of hyperactive DNase I mutants that combine high catalytic activity with temperature-sensitive stability. The enzyme maintains high productivity at low temperatures during incubation but becomes inactivated at 50-65°C, preventing interference with subsequent RNA detection while maintaining efficient DNA degradation.
Solution Approach 2:
The patent uses periodic action by incubating the heat-labile hyperactive DNase I at optimal temperature for DNA degradation, then applying heat to inactivate the enzyme before proceeding with reverse transcription. This temporal separation ensures high degradation activity when needed and zero activity when it would cause interference.
3Stability of the object's composition
If standard DNase I is used, then the enzyme is stable and easy to handle, but it lacks the hyperactivity needed for efficient DNA degradation in complex samples
Solution Approach 1:
The patent introduces specific amino acid substitutions (K74, R9, E13, N74) that change the catalytic parameters of DNase I to create hyperactive variants with 10-100 fold increased activity. These parameter changes in catalytic efficiency are combined with heat-labile mutations to maintain manageable stability characteristics.
Solution Approach 2:
The patent creates composite enzyme molecules by combining hyperactive mutations with heat-labile mutations in a single DNase I polypeptide. This composite structure integrates both high catalytic activity and temperature-sensitive stability, achieving a balance between productivity and controllability that neither mutation type provides alone.
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 heat-labile, hyperactive DNases effectively degrade DNA in samples, allowing for subsequent RNA detection and analysis without the need for separate DNA removal steps, while the fusion with DNA binding domains improves activity and stability.
Implementation Method 1
DNases are useful for removing or degrading DNA from samples containing RNA and/or protein
Implementation Method 2
the DNase is heat-labile, thereby allowing for heating of a reaction to substantially eliminate DNase activity
Data Source
AI summary
Modified DNase polypeptides and methods of their use are provided.