Cyclen-Based Chelator Segmentation for Peptide Metal Positioning
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Solution Overview
Problem
Current methods for incorporating rare earth elements into peptides for biomedical applications face challenges such as instability, toxicity, and difficulty in controlling the position and rotational motion of metal chelates within the peptide chain.
Innovation Solution
The development of amino acid chelator building blocks that combine stability with rare earth elements, allowing for incorporation into peptide chains through standard solid-phase peptide synthesis, and enabling the precise control of metal positions within the peptide sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bifunctional chelators are used to bind metal ions and allow covalent attachment to peptides, then the metal can be linked to targeting vectors for directed delivery, but the functional group needed for conjugation may become coordinated to the metal ion, making it unreactive for the conjugation reaction
Solution Approach 1:
The chelator is divided into separate functional segments: a metal-binding domain (cyclen-based chelating groups) and a conjugation domain (carboxylic acid or amine groups). This spatial separation ensures that the conjugation functional groups remain accessible and reactive while the metal-binding domain maintains stable coordination, resolving the conflict between metal binding stability and conjugation reactivity
Solution Approach 2:
The patent introduces intermediary linkers or spacer groups between the metal-chelating core and the peptide conjugation sites. These intermediaries act as mediators that prevent the conjugation functional groups from coordinating to the metal ion while still allowing covalent attachment to the peptide, thus maintaining both metal binding stability and conjugation reactivity
2Productivity
If conjugation occurs at multiple positions on the peptide molecule, then the peptide can be synthesized using standard solid-phase peptide synthesis, but a mixture of products is obtained that needs to be separated
Solution Approach 1:
The chelator is designed with non-uniform distribution of functional groups, creating distinct regions with different reactivities. The peptide sequence is engineered to contain a specific recognition motif or unique functional group at the desired conjugation site, ensuring that conjugation occurs selectively at that specific position rather than at multiple positions, thereby achieving both efficient synthesis and precise position control
Solution Approach 2:
The chelator is pre-modified with protecting groups or activating moieties that enable site-selective conjugation before peptide synthesis. By preparing the chelator with predetermined reactive groups at specific positions, the conjugation can be controlled to occur at a single defined location on the peptide, avoiding mixture formation while maintaining high productivity
3Stability of the object's composition
If the carboxylic group needed for peptide coupling coordinates to the metal ion, then stable metal chelate is formed, but the carboxylic group becomes unreactive for the conjugation reaction
Solution Approach 1:
The chelator structure is segmented into distinct functional modules: metal-binding carboxylic acid groups that form stable chelates, and separate conjugation functional groups (such as amines or hydroxyls) that remain uncoordinated and reactive. This modular design allows simultaneous achievement of stable metal binding and retained conjugation capability
Solution Approach 2:
The patent utilizes spatial arrangement in three-dimensional space to resolve the conflict. The chelator is designed with a specific geometry where metal-coordinating groups are oriented in one spatial direction (forming stable chelate), while conjugation functional groups are positioned in a different spatial dimension or orientation, making them accessible for peptide coupling reactions without interfering with metal binding
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
These cyclen-based compounds provide stable metal chelates, allow for the combination of different metals within a single peptide molecule, and restrict the rotational motion of metal chelates, enhancing the functionality and efficiency of the resulting peptide-based imaging or therapeutic agents.
Implementation Method 1
bind the metal in a stable chelate to suppress the toxicity of the free metal ions
Implementation Method 2
Stable, non-radioactive Gd chelates are in clinical use as contrast agents for Magnetic Resonance Imaging (MRI)
Data Source
AI summary
Cyclen based compounds of general formula (I) are disclosed. X is nitrogen and Y, Z are —CH—, or X, Z are —CH— and Y is nitrogen, or X, Y are —CH— and Z is nitrogen. R1 is independently selected from H; COOH; benzyloxycarbonyl; fluorenylmethyloxycarbonyl; tert-butoxycarbonyl; methylcarbonyl; trifluoromethylcarbonyl; benzyl; triphenylmethyl; tosyl; mesyl; benzyloxymethyl; phenylsulfonyl; ethoxycarbonyl; 2,2,2-trichloroethyloxycarbonyl; methoxycarbonyl; methoxymethyloxycarbonyl; R2 is selected from H; methylcarbonyl; tert-butyldimethylsilyl; (C1-C4)alkyl; R3 is independently selected from H; (C1-C6)alkyl.