geting peptides such as cholecystokinin/gastrin analogues, glucagon-like peptide-1, bombesin (BN

It seems like you're asking about how to obtain peptides like cholecystokinin/gastrin analogues, glucagon-like peptide-1, and bombesin. Here's a general step-by-step process:

1. Design the Peptide Sequence: The first step in obtaining these peptides is to design the peptide sequence. This is usually done using bioinformatics tools and databases to identify the sequence of the peptide in the target organism.

2. Peptide Synthesis: Once the peptide sequence has been identified, the next step is to synthesize the peptide. This is usually done using solid-phase peptide synthesis (SPPS), a method that involves the sequential addition of amino acids to a growing peptide chain.

3. Purification: After the peptide has been synthesized, it needs to be purified to remove any unwanted byproducts from the synthesis process. This is usually done using high-performance liquid chromatography (HPLC).

4. Verification: The final step is to verify the identity and purity of the peptide. This is usually done using mass spectrometry and analytical HPLC.

Please note that this is a simplified explanation and the actual process can be quite complex and requires specialized knowledge and equipment. Also, some peptides may need to be modified after synthesis to improve their stability or activity, which adds additional steps to the process.