Polypeptide customization generally refers to a kind of service of artificial polypeptide synthesis, which refers to the polypeptide synthesis service which meets the specific needs according to the needs of customers, such as sequence, purity, molecular weight and so on. The molecular weight of crude MS was confirmed by mass spectrometer, and then the crude product was purified by high performance liquid chromatography (HPLC) to obtain fine peptide. According to different experiments, different polypeptide purity can be selected, in principle, the higher the purity, the higher the price.
The number of amino acids in general peptides is two to nine. According to the number of amino acids in peptides, peptides have many different names: the compound formed by dehydration and condensation of two amino acid molecules is called dipeptide, and by analogy, there are tripeptide, tetrapeptide, pentapeptide and so on.
Usually, the compounds formed by dehydration and condensation of 10 × 100 amino acid molecules are called polypeptides. Their molecular weight is lower than that of 10000Da (dalton, Dalton). They can pass through the semi-permeable membrane and can not be precipitated by trichloroacetic acid and ammonium sulfate.
The peptide composed of 2 and 10 amino acids is called oligopeptide (oligopeptide), the peptide composed of 10 and 50 amino acids is called polypeptide, and the peptide composed of more than 50 amino acids is called protein. In other words, protein is sometimes also called polypeptide.
