Recombinant Endotoxin Assay Cascade for Faster, More Sensitive Detection
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Solution Overview
Problem
Existing methods for measuring endotoxin are limited by the need for horseshoe crabs, slow reaction times, and insufficient sensitivity, posing challenges for rapid and cost-effective detection.
Innovation Solution
A method using recombinant factor C, factor B, and proclotting enzyme derived from Japanese horseshoe crabs, expressed in insect cells, which are produced without C-terminal peptides, enabling rapid and sensitive endotoxin measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If horseshoe crab lysate or naturally occurring factors are used for endotoxin detection, then the measurement can be performed using conventional methods, but the supply is limited due to conservation concerns and the measurement takes over an hour with sensitivity only up to 0.001 EU/mL
Solution Approach 1:
The patent uses recombinant proteins (factor C, factor B, and proclotting enzyme) produced through genetic engineering in insect cells as copies of the natural horseshoe crab factors. This copying approach replaces the need for actual horseshoe crab lysate, enabling unlimited supply while improving measurement sensitivity to 0.0005 EU/mL and reducing measurement time to 30 minutes or less.
Solution Approach 2:
The patent optimizes the cascade reaction system by using recombinant proteins with modified properties compared to natural factors. The recombinant factor C lacks the signal peptide sequence present in natural factor C, and the combination of recombinant proteins enables faster reaction kinetics, achieving 50% coagulation within 30 minutes while maintaining high sensitivity.
2Quantity of substance
If recombinant proteins are used to reconstruct the cascade reaction system, then unlimited supply is possible, but the measurement requires 1 hour or more and achieves detection sensitivity of only 0.001 EU/mL
Solution Approach 1:
The patent creates a composite endotoxin detection system by combining three different recombinant proteins (factor C, factor B, and proclotting enzyme) produced through genetic engineering. This composite approach using insect cell-expressed proteins achieves both unlimited supply capacity and superior detection sensitivity of 0.0005 EU/mL, outperforming previous recombinant systems.
3Quantity of substance
If recombinant proteins are used to reconstruct the cascade reaction system, then unlimited supply is possible, but the measurement takes 1 hour or more
Solution Approach 1:
The patent uses recombinant proteins produced through genetic engineering as copies of natural horseshoe crab factors, enabling unlimited supply while achieving rapid measurement completion within 30 minutes through optimized reaction kinetics of the recombinant protein mixture.
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 detection sensitivity of 0.0005 EU/mL within 30 minutes, facilitating low-cost and efficient endotoxin measurement without the need for purification.
Implementation Method 1
This method is called 'limulus test', and uses a cascade reaction of various proteins existing in the lysate, which reaction is caused by contacting of endotoxin with the lysate
Implementation Method 2
This clotting enzyme hydrolyzes a specific portion in the coagulogen molecule existing in the lysate. By this, coagulin gel is produced, to cause coagulation of the lysate
Implementation Method 3
a clotting enzyme reacts with a synthetic substrate t-butoxycarbonyl-leucyl-glycyl-arginyl-pNA (Boc-Leu-Gly-Arg-pNA) to hydrolyze its amide bond, and thereby pNA is released. Thus, by preliminarily including the synthetic substrate in the reaction system, endotoxin can be quantified by measurement of the absorbance (405 nm) of the coloring substance (pNA)
Data Source
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AI summary
A method for rapidly and highly sensitively measuring endotoxin is provided. Endotoxin is measured using an endotoxin-measuring agent comprising the proteins (1) to (3) below, each of which is a recombinant protein obtainable by being expressed using insect cells as a host: (1) a factor C derived from Tachypleus tridentatus, which factor C does not have a His-tag sequence at the C-terminus; (2) a factor B of a horseshoe crab; and (3) a proclotting enzyme of a horseshoe crab.