Site-Directed Mutagenesis Libraries involve replacing customer-specified amino acid residues sequentially with each of the remaining 19 amino acids to create mutant libraries. This approach enables scientists to perform structure–function analyses to examine the benefits or drawbacks of specific amino acid substitutions.

Figure 1. Site-directed Mutagenesis Library

Scanning Libraries are one of the core types of customized gene libraries. By systematically substituting specific amino acid residues or regulatory sequences of the target protein, these libraries reveal their impact on structure, function, and interactions. They are widely applied in protein engineering, antibody optimization, and drug target screening. Alanine scanning and cysteine scanning are two commonly used approaches in scanning libraries.

Figure 2. Scanning Mutagenesis Library

Random Mutagenesis Libraries are generated by introducing nucleotide mutations randomly into gene sequences using specific methods, producing a mixture of mutated genes. These mutations may involve single-base substitutions, insertions, or deletions. The purpose is to introduce diversity through mutagenesis, enabling the screening of mutants with desired functions or properties.

Figure 3. Random Mutagenesis Library

By combining different genetic elements in multiple ways, scientists can create mutant libraries to identify beneficial combinations. We provide both conventional partially randomized (NNK/NNS) and fully randomized (NNN) combinatorial library services.

Figure 4. Combinatorial Library

Truncation libraries are constructed by trimming amino acids from the N-terminal, the C-terminal around a designated core region of the protein, or both. This approach enables scientists to determine the core regions responsible for the protein’s function.

Figure 5.Truncation Library

1. Low library transformation efficiency.

Answer: Possible causes include low adapter ligation efficiency and low purification recovery rates.

Solution: Optimize adapter ligation conditions to ensure ligation efficiency, and use highly efficient purification methods to improve recovery rates.

2. Mutation frequency and diversity of the variant library do not meet expectations.

Answer: Possible causes include suboptimal error-prone PCR conditions, resulting in mutation frequencies being either too low or too high, and improper design of degenerate codons, leading to insufficient mutation diversity.

Solution: Optimize error-prone PCR conditions by adjusting dNTP concentration, Mg²⁺ concentration, or adding Mn²⁺; design degenerate codons rationally to ensure sufficient mutation diversity.

3. Library fragment length smaller or larger than expected.

Answer: Possible causes include inappropriate fragmentation time or temperature, or residual inhibitors from sample extraction affecting fragmentation efficiency.

Solution: Optimize fragmentation time and temperature to ensure the desired fragmentation effect. Extend fragmentation time or remove inhibitors of the fragmentation enzyme. Use capillary electrophoresis to verify library fragment length and ensure compliance with requirements. If you require specific technical assistance, please contact our sales support team.