SAH1 Polypeptide Cyclic Modification for Tuberculosis Treatment
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Solution Overview
Problem
Current antimicrobial peptides, such as BMAP-18, exhibit high cytotoxicity and unsatisfactory antibacterial effects against Mycobacterium tuberculosis, limiting their potential as therapeutic agents for tuberculosis.
Innovation Solution
A novel polypeptide, SAH1, with a modified sequence and structure, is developed through point mutations and a dehydration-condensation reaction with dimethylolurea, resulting in a polypeptide with reduced cytotoxicity and enhanced anti-Mycobacterium tuberculosis activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BMAP-18 is used as an antimicrobial peptide, then antibacterial activity is improved, but cytotoxicity increases
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of BMAP-18 through point mutations (F4C and C8C mutations introducing cysteine residues at positions 4 and 8). These structural parameter changes enable cyclic bond formation while reducing cytotoxicity. The modified peptide SAH1 maintains antibacterial activity against Mycobacterium tuberculosis while exhibiting significantly reduced cytotoxicity to mammalian cells compared to the original BMAP-18.
2Reliability
If conventional TB drugs are used, then treatment effectiveness is improved, but drug toxicity and resistance increase
Solution Approach 1:
The patent extracts the core antibacterial function from conventional TB drugs by developing a peptide-based therapeutic agent that targets Mycobacterium tuberculosis through a different mechanism. Instead of using traditional antimicrobial compounds with known toxicity and resistance issues, the invention extracts and utilizes the antimicrobial properties of modified bovine peptides, specifically SAH1, which acts through pore formation and membrane disruption mechanisms distinct from conventional drugs.
3Reliability
If BMAP-27 is used, then killing activity against microorganisms is improved, but cytotoxicity increases
Solution Approach 1:
The patent applies segmentation by truncating the full-length BMAP-27 peptide (27 amino acids) to create BMAP-18 (18 amino acids), and further modifying it to create SAH1 with cyclic bonds. This segmentation and structural modification reduces the peptide's size and adjusts its amphiphilic properties, maintaining microorganism-killing activity while reducing cytotoxic effects on mammalian cells.
Solution Approach 2:
The patent creates a composite structural feature by introducing cyclic bonds through disulfide bridges between cysteine residues at positions 4 and 8. This composite structure combines the linear peptide backbone with cyclic constraints, creating a rigid amphiphilic structure that enhances membrane-targeting capability while reducing non-specific cytotoxicity. The cyclic modification creates a more stable and selective antimicrobial agent.
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
SAH1 demonstrates significantly lower cytotoxicity to mouse macrophages and improved antibacterial effects against Mycobacterium tuberculosis, including strong anti-BCG bacterial infection capabilities and resistance to protease hydrolysis, making it a promising candidate for tuberculosis treatment.
Implementation Method 1
allowing sulfhydryl groups of two cysteine residues in the straight-chain polypeptide to undergo a dehydration-condensation reaction with dimethylolurea to obtain the polypeptide
Data Source
AI summary
A polypeptide with an anti-Mycobacterium tuberculosis activity, and a preparation method and use thereof are provided. The preparation method of the polypeptide includes the following steps: (1) preparing a straight-chain polypeptide with a sequence shown in SEQ ID NO: 1; and (2) allowing sulfhydryl groups of two cysteine residues in the straight-chain polypeptide to undergo a dehydration-condensation reaction with dimethylolurea to obtain the polypeptide. The polypeptide has little cytotoxicity and a prominent anti-Mycobacterium tuberculosis effect.