Cyclin-Dependent Kinase Substrate Peptide for CDK4/6 Activity
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Solution Overview
Problem
Current methods for evaluating cyclin-dependent kinase 4 and 6 activity, particularly using RB protein as a substrate, face challenges due to high production costs and stability issues, and commercially available substrate peptides with the optimal consensus sequence have low reactivity and specificity.
Innovation Solution
A cyclin-dependent kinase substrate polypeptide with a specific amino acid sequence where the second residue from the proline in the phosphorylation site is an aromatic amino acid and/or at least two residues from the proline towards the C-terminal are acidic, enhancing reactivity and specificity to cyclin-dependent kinase 4 and 6.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RB protein is used as a substrate to evaluate cyclin-dependent kinase 4 or 6 activity, then detection accuracy is improved, but manufacturing cost increases and stability deteriorates
Solution Approach 1:
The invention extracts the essential functional region of the RB protein (amino acids 780-826) to create a smaller substrate peptide. This extracted peptide retains the ability to be phosphorylated by cyclin-dependent kinases while eliminating the problems of high cost and poor stability associated with using the full-length RB protein.
Solution Approach 2:
The invention creates a simplified copy of the RB protein's phosphorylation site. Instead of using the complete RB protein, a peptide copy containing the critical amino acid sequence is synthesized, which can be produced more easily and stored more stably while maintaining detection functionality.
2Ease of manufacture
If a substrate peptide with the optimal consensus sequence (S/T) PX (K/R) is used, then ease of manufacture is improved, but reactivity and specificity deteriorate
Solution Approach 1:
The invention modifies the generic consensus sequence by introducing specific local characteristics - the Proline-directed motif with specific amino acids at positions -2 and +1 relative to the phosphorylation site. This local optimization of the peptide sequence enhances binding affinity and specificity for cyclin-dependent kinases 4 and 6 while maintaining ease of synthesis.
Solution Approach 2:
The invention changes the amino acid composition parameters of the substrate peptide to optimize reactivity. Specifically, it incorporates a Proline residue at the P position and selects specific amino acids for the -2 and +1 positions to create optimal interaction with the kinase active site, thereby enhancing both reactivity and specificity.
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 substrate polypeptide significantly improves reactivity and specificity to cyclin-dependent kinase 4 and 6, offering a more effective tool for evaluating their activity compared to existing methods.
Implementation Method 1
The activity of cyclin-dependent kinase is mainly a phosphorylated enzyme... by detecting phosphorylation using specific antibodies
Data Source
AI summary
Disclosed is a cyclin-dependent kinase substrate including a polypeptide that contains an amino acid sequence represented by formula (1): R1—P (wherein R1 represents a serine residue or a threonine residue, P represents a proline residue, “—” represents a single bond, and the left side represents the N-terminal side), and satisfies the following (a1) and/or (b1): (a1) the second amino acid residue counting from the proline residue toward the N-terminal side in the formula (1) is an aromatic amino acid residue, and/or (b1) at least two amino acid residues from the proline residue toward the C-terminal side in the formula (1) are acidic amino acid residues.