PapB Thioether Crosslinking for Site-Specific Peptide Modification
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Solution Overview
Problem
Existing synthetic chemistry methods are limited in their ability to rapidly and specifically modify peptides to introduce thioether linkages, which are crucial for enhancing the stability and diversity of peptide-based therapeutics.
Innovation Solution
Employing the PapB enzyme, a ribosomally synthesized and post-translationally modified peptide (RiPP) maturase, to catalyze the insertion of thioether crosslinks in peptides, particularly at the Cβ or Cγ positions of specific residues, using a radical S-adenosylmethionine (rSAM) mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If synthetic chemistry methods are used to modify peptides, then thioether linkages can be introduced, but the process is slow and lacks specificity
Solution Approach 1:
The patent employs PapB enzyme as a biocatalyst (intermediary) to mediate the formation of thioether linkages between cysteine and aspartic acid/glutamic acid residues. This enzymatic approach provides both high reaction rate (productivity) and site-specific modification (precision), resolving the contradiction between speed and specificity that plagues conventional synthetic chemistry methods.
Solution Approach 2:
The patent replaces mechanical/chemical synthesis methods with a biological enzymatic system. The PapB enzyme utilizes a radical S-adenosylmethionine (rSAM) mechanism to catalyze thioether bond formation, substituting the need for complex chemical reagents and conditions with a highly specific biological catalyst that operates under milder conditions with greater precision and efficiency.
2Adaptability or versatility
If enzymatic reactions are used to access vast chemical space, then diversity of peptide structures is improved, but the complexity of the enzymatic system increases
Solution Approach 1:
The PapB enzyme demonstrates universality by accepting multiple substrate variants including different amino acid sequences, varying lengths, and multiple CX3D motifs within a single peptide. This multi-functional capability allows the enzyme to access diverse chemical spaces while maintaining a single, relatively simple enzymatic system, resolving the contradiction between versatility and complexity.
Solution Approach 2:
The enzyme system exhibits dynamic adaptability through its ability to process various substrate conformations and sequences. The PapB enzyme can accommodate different peptide structures and modification patterns, allowing the system to explore vast chemical space without requiring a complex array of specialized enzymes for each variant.
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
Enables rapid and highly specific installation of thioether linkages in a broad range of peptides, accessing unique chemical spaces and improving the stability and therapeutic potential of peptide-based drugs.
Implementation Method 1
This superfamily has been implicated in a variety of RiPP modifications, including C—C, C—N, C—O and C—S bond formation at unactivated carbons via radical mechanisms.
Implementation Method 2
PapB is a RiPP maturase that catalyzes the insertion of six thioether crosslinks in the PapA polypeptide.
Implementation Method 3
When the RS cluster is catalytically active, it transfers an electron to bound SAM. Homolytic cleavage of SAM forms the reactive 5′-deoxyadenosyl radical (5′-dAdo, FIG. 1).
Data Source
AI summary
The present disclosure is concerned with methods of chemically modifying a peptide sequence to install a thioether linkage, the method comprising reacting the peptide sequence with PapB. Also disclosed are compounds produced by such methods that may be useful in, for example, peptide therapeutic uses. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.