Larazotide Peptide

In solid-phase peptide synthesis, the first step is to select a suitable resin as the solid-phase carrier. Commonly used resins include Wang resin, Rink Amide resin, etc. They have different linking groups and chemical stability, and can be selected according to the properties of the target peptide. Place the resin in a reactor, add an appropriate amount of dichloromethane (DCM) or N, N-dimethylformamide (DMF) for swelling, and then use reagents such as pyridine or hexahydropyridine to remove the Fmoc or Boc protecting groups on the resin, exposing the amino groups on the resin for the next coupling reaction.

Dissolve amino acids with protective groups (such as Fmoc Gly OH, Fmoc Val OH, etc.) in DMF, add coupling reagents (such as HBTU, HATU, DIC, etc.) and activators (such as HOBt), mix thoroughly, and add to a reactor containing activated resin. Under appropriate temperature (usually room temperature) and stirring conditions, amino acids undergo condensation reactions with amino groups on the resin, forming peptide bonds. After the coupling reaction is completed, wash the resin with DMF to remove unreacted amino acids and reagents.

Use pyridine or hexahydropyridine to remove the Fmoc or Boc protecting group on the newly coupled amino acid, allowing the next amino acid to be coupled. Repeat the above coupling and deprotection steps, sequentially connecting amino acids such as glycine, valine, leucine, valine, glutamine, proline, and glycine to the resin until the synthesis of the entire Larazotide peptide chain is completed.

After all amino acids have been coupled, remove the resin from the reactor and stir the reaction at room temperature with a cutting reagent (such as a mixed solution of trifluoroacetic acid, phenol, water, triisopropylsilane, etc.) for several hours to cut the peptide chain from the resin and remove the protective group on the amino acid side chain. After the cutting reaction is completed, filter and remove the resin, and collect the filtrate. The filtrate was precipitated in ice ether and centrifuged to obtain the crude peptide. The crude peptide was purified by high performance liquid chromatography (HPLC) to remove impurities and by-products, resulting in high-purity Larazotide.

Choose an appropriate protective strategy and divide the Larazotide chain into several shorter fragments, which are synthesized separately in the liquid phase. For example, small fragments such as dipeptides and tripeptides can be synthesized first. During the synthesis process, amino acids with protective groups are gradually coupled in appropriate solvents (such as DMF, DCM, etc.) under the action of coupling reagents and activators to form the target fragment. After each fragment is synthesized, it needs to be purified and characterized to ensure its purity and correct structure.

Conjugate the synthesized fragments in liquid phase to obtain the complete Larazotide chain. Fragment coupling usually uses methods such as activated ester method and mixed anhydride method. For example, converting the carboxyl group of one fragment into an activated ester, and then reacting with the amino group of another fragment to form a peptide bond. After the coupling reaction is completed, the product needs to be purified and characterized to remove unreacted fragments and by-products.

Divide a large number of resin beads into several equal parts, and attach a different amino acid or fragment to each resin bead. Then, mix these resin beads together and proceed to the next coupling reaction. Through multiple processes of segmentation, synthesis, and mixing, a large number of Larazotide analogs can be synthesized in a short period of time.

After synthesis, screen the peptide library for Larazotide analogs with specific biological activities. The screening methods can use techniques such as biological activity assay and high-throughput screening. Structural identification and further research of the screened active compounds provide a basis for the structural optimization and drug development of Larazotide.