Single-Chain Fab Antibody for High-Affinity Cell-Free Expression

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Solution Overview

Problem

Traditional small molecule recombinant antibodies, such as scFv and Fab, face issues of low affinity, poor stability, and low expression efficiency, limiting their commercial application and industrialization.

Innovation Solution

A single-chain antibody (scFab) is developed, connecting an antibody light chain or light chain fragment to a heavy chain or heavy chain fragment via a linker, optimized with specific amino acid compositions and lengths, enabling high expression efficiency and affinity, and synthesized in an in vitro cell-free system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional scFv antibodies are used, then expression efficiency is improved, but affinity and stability deteriorate

Engineering Contradiction:

Improveexpression efficiencyVSAvoidaffinity and stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent merges the light chain and heavy chain variable regions into a single continuous polypeptide chain using a linker, creating scFv antibodies that maintain high expression efficiency while improving affinity and stability through optimized structural integration

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies parameter changes by optimizing the linker sequence and length between variable regions, adjusting amino acid compositions to enhance both expression efficiency and antibody stability without sacrificing affinity

Inventive Principle:

Principle #35Parameter changes

2Reliability

If Fab fragments are used, then affinity is improved, but expression efficiency and complexity worsen

Engineering Contradiction:

ImproveaffinityVSAvoidexpression efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent segments the Fab fragment structure into essential variable regions connected by a linker, eliminating the need for complex disulfide bond formation and separate chain expression while maintaining affinity, thereby improving expression efficiency

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If small molecule antibodies are used, then ease of production is improved, but stability deteriorates

Engineering Contradiction:

Improveease of productionVSAvoidstability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent creates a composite structure by combining variable regions from both light and heavy chains into a single-chain format with optimized linkers, achieving enhanced stability while maintaining the ease of production characteristic of small molecule antibodies

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP4692127A1Single-chain antibody and in vitro synthesis system and use thereof

Publication Date: 2026.02.11 KANGMA (SHANGHAI) BIOTECH LTD

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AI summary

The present invention provides a single-chain antibody and an in vitro synthesis system and use thereof. The antibody has a high expression efficiency, high affinity and high stability, is high-efficiently expressed in one step in an in vitro cell-free synthesis system without secreting and expressing two different protein fragments of a light chain and a heavy chain, respectively, which is not easy to form a homodimer, has a relatively high expression efficiency, can be produced on a large scale, and has a good prospect of commercialization.