Part:BBa_K5466014

AntiAFB1-scFv2. Saccharomyces cerevisiae codon optimized without STOP codon

AntiAFB1-scFv2 (BBa_K2247007) from iGEM17_Tsinghua, without a STOP codon to be used as a ligand binding domain for AFB1 with other protein domains. For example, in our project, it is the LBD of a composite part, a Patrol Yeast receptor, fused with EpoR and Cub (BBa_K5466019), to detect AFB1.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

scFv

A single-chain variable fragment (scFv) is not a fragment of an antibody; it is a fusion protein made up of the variable regions of the heavy (VH) and light (VL) chains of immunoglobulins, linked together by a short peptide linker consisting of ten to twenty-five amino acids. This linker is typically rich in glycine, providing flexibility, along with serine or threonine to enhance solubility. It can connect either the N-terminus of the VH to the C-terminus of the VL or the other way around. Despite the absence of the constant regions, this protein maintains the specificity of the original immunoglobulin due to its structural integrity.

They retain the binding specificity of the original antibody and offer several advantages over full-length monoclonal antibodies. These benefits include the elimination of unwanted side effects associated with the Fragment crystallizable region (the truk of the Y shape) of complete antibodies, ease of construction and expression, and the ability for large-scale production. scFvs also exhibit improved pharmacokinetic properties, resulting in fewer or no hypersensitivity or rejection reactions. The stability of the fragments is crucial to ensure the successful application of scFvs in both in vitro and in vivo settings.

Each of the two variable domains in an scFv contains three hypervariable or complementary determining regions (CDRs), linked by framework regions (FRs). The CDRs are responsible for antigen binding and are structured to complement the epitope, while the framework regions serve as a stable scaffold with minimal variability compared to the CDRs. Interestingly, the contribution of each CDR to antigen binding differs significantly. For example, the CDR3 of the heavy chain is particularly important, contributing 29% to binding specificity, whereas CDR2L accounts for only 4% of the specificity.

More information in this specific scFv in iGEM17_Tsinghua part registry page (BBa_K2247007).

References

Muñoz-López, P., Ribas-Aparicio, R. M., Becerra-Báez, E. I., Fraga-Pérez, K., Flores-Martínez, L. F., Mateos-Chávez, A. A., & Luria-Pérez, R. (2022). Single-Chain Fragment Variable: Recent progress in cancer diagnosis and therapy. Cancers, 14(17), 4206. https://doi.org/10.3390/cancers14174206