ADAMTS13 Polypeptide Substrate Autofluorescence Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current ADAMTS13 activity assays using the FRETS-VWF73 substrate suffer from high autofluorescence noise, sensitivity issues, and non-linear calibration curves, leading to inaccurate results, particularly in diagnosing and monitoring Thrombotic Thrombocytopenia Purpura (TTP), where precise ADAMTS13 activity between 0-10% is crucial.
Innovation Solution
A novel ADAMTS13 polypeptide substrate with specific amino acid mutations and modifications, such as changing Q to K at position 1599 and N to C at 1610, and deleting Q1624 to R1641, along with the inclusion of detectable labels like fluorophores and quenchers, is developed to improve assay accuracy and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FRETS-VWF73 substrate is used for ADAMTS13 assay, then the assay can be performed with a polypeptide substrate, but the autofluorescence noise is high and sensitivity is poor
Solution Approach 1:
The patent modifies the polypeptide substrate by changing amino acid positions (Q1599K, N1610C) and deleting specific regions (Q1624-R1641) to alter its fluorescent properties. These parameter changes in the substrate structure reduce autofluorescence noise while maintaining ADAMTS13 cleavage activity, thereby improving measurement precision without being affected by the harmful autofluorescence factor.
2Measurement precision
If FRETS-VWF73 substrate is used, then ADAMTS13 activity can be measured, but the calibration curve is non-linear resulting in low accuracy below 10% activity
Solution Approach 1:
The patent introduces specific amino acid modifications (Q1599K, N1610C) and deletions (Q1624-R1641) to the polypeptide substrate structure. These parameter changes in the substrate's amino acid sequence improve the linearity of the calibration curve across the full range of ADAMTS13 activity (0-100%), enabling accurate measurement even at low activity levels below 10% where the original substrate failed.
3Quantity of substance
If SEQ ID NO:6 polypeptide is synthesized, then ADAMTS13 substrate is available, but de novo synthesis is difficult and sensitivity is poor
Solution Approach 1:
The patent simplifies the polypeptide substrate structure by deleting the difficult-to-synthesize Q1624-R1641 region and modifying specific amino acids (Q1599K, N1610C). These parameter changes make the substrate easier to manufacture through de novo synthesis while maintaining sufficient quantity and activity for sensitive ADAMTS13 measurement.
4Ease of operation
If homogeneous assay is performed without washing, then the assay is simplified, but autofluorescence noise from plasma is exacerbated
Solution Approach 1:
The patent converts the harmful plasma autofluorescence into a beneficial situation by using a substrate with inherently low autofluorescence properties. The modified substrate (with Q1599K, N1610C, and Q1624-R1641 deletion) produces minimal background noise, allowing the homogeneous assay to proceed without washing steps while maintaining high signal-to-noise ratio and simplicity of operation.
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 new substrate provides a reliable, linear calibration curve, higher sensitivity, and faster reaction times, enabling precise determination of ADAMTS13 activity in the range of 0-20%, enhancing the differential diagnosis of TTP and its management.
Implementation Method 1
The detectable label is a fluorophore and a quencher
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a first aspect, there is provided an isolated polypeptide substrate for a disintegrin-like and metallopeptidase with thrombospondin type-1 motif, 13 (ADAMTS13) that is from 45 to 70 amino acids in length and has an amino acid sequence that is substantially similar to part of the von Willebrand factor A2 domain sequence set forth in SEQ ID NO:2, with one or more of the following modifications: (i) the amino acid corresponding to position 1599 of SEQ ID NO: 2 is mutated from Q to K; (ii) the amino acid corresponding to position 1610 of SEQ ID NO: 2 is mutated from N to C; and (iii) the amino acids corresponding to Q1624 to R1641 of SEQ ID NO: 2 are deleted. In another aspect, there is provided an ADAMTS13 polypeptide substrate that is from 50 to 75 amino acids in length and has an amino acid sequence that is substantially similar to part of the von Willebrand factor A2 domain sequence set forth in SEQ ID NO:2, with one or more of the following modifications: (i) the amino acid corresponding to position 1599 of SEQ ID NO: 2 is mutated from Q to K; (ii) the amino acid corresponding to position 1610 of SEQ ID NO: 2 is mutated from N to C; (iii) the amino acid corresponding to position 1629 of SEQ ID NO: 2 is mutated from G to E; and (iv) the amino acids corresponding to G1631 to R1641 of SEQ ID NO: 2 are deleted.