Synthesis of peptides is a complex process that usually involves different synthesis strategies and techniques. The following are some common approaches to peptide synthesis processes and techniques:

Solid-Phase Synthesis
This is one of the most commonly used methods for peptide synthesis. It is based on the stepwise addition of amino acid units on a solid-phase support to build peptide chains. The solid phase support materials typically used are highly reactive resins such as Rink-Amide or Fmoc-AM resin. During the synthesis process, the amino acid unit is immobilized on the solid phase by a reactive protecting group, followed by coupling, deprotection and elution to finally obtain the target peptide.

Solution-Phase Synthesis
This method synthesizes peptides in solution. It is usually applied to shorter peptide chains. In solution-phase synthesis, the amino acid unit is coupled to other amino acids in a coupling reaction via an activator (e.g., an activated acid or an activated carboxylic acid). After the reaction, steps such as removal of protective groups and purification are required to obtain a pure peptide product.

Chemical Synthesis
Chemical synthesis is a technique for synthesizing peptide by methods of organic synthesis. It usually involves a reaction using chemical reagents such as protecting groups, activators and solvents. Chemical synthesis methods can be used to synthesize complex peptide structures, but are more challenging for long chain peptides due to the number of steps and the potential for side reactions.

Biosynthesis
Biosynthesis is the synthesis of peptides using cellular mechanisms and enzymes in the organism. This method is commonly used in the synthesis of natural peptides, such as in the production of hormones and peptide drugs. Through genetic engineering techniques, genes encoding peptide are introduced into appropriate expression systems to synthesize the target peptide within the cell.

These synthetic methods are widely used in the field of peptide drugs. Each method has its advantages and limitations, and the choice of synthesis depends on factors such as peptide structural complexity, target purity requirements, scale and economics. Researchers choose the most suitable synthesis strategy and technique based on the specific synthesis needs.