The solubility of the peptide depends on the physical properties calculated by the element. Amino acids can be classified as acidic, basic, polar, non-polar, and hydrophobic. Peptides have a high content of non-polar hydrophobic amino acids or polar uncharged amino acids. It is recommended to dissolve in organic solutions (eg DMF, methanol, propanol, isopropanol, DMSO). In short, acidic polypeptides are generally dissolved in alkaline solutions, while alkaline polypeptides are dissolved in acidic solutions. Amino acid properties Alkaline: Arg, His (H), Lys (K) Non-polar hydrophobicity: Ala (A), Ile (I), Len (L), Met (M), Phe (F), Pro (P), Trp (W), Val (V) Polarity without charge: Asn (N), Cys (C), Glg (G), Gln (Q), Ser (S), Thr (T), Tyr (Y) Acidity: Asp (D), Glu (E) Bachem publishes the product analysis report (ADS) for each batch number, providing solubility in special solutions. The customer can dissolve the peptide according to the solution in the product analysis report as appropriate. Or the customer can test the solubility of the peptide in a small amount of samples according to the following method. Because the solubility characteristics of the polypeptide depends on its amino acid composition. Before choosing the appropriate solvent, we suggest to check the amino acid sequence of the peptide. 1. Basic peptides (number of basic amino acids> number of acidic amino acids) should first be dissolved with a small amount of acidic amino acid solution (for example: acetic acid or trifluoroacetic acid), and then the required concentration of diluent. When preparing high-concentration stock solutions, 80% acetic acid should be used to dissolve the peptides. It can also be dissolved with 20% acetic acid to reduce the adverse effects of acetic acid on the detection system. 2. For acidic peptides (number of acidic amino acids> number of basic amino acids), a small amount of basic amino acid solution (eg 0.1% ammonia water, NH4OH) should be used first, and then diluted with water to the desired concentration. It should be noted that for peptides containing cysteine ​​(Cysteine), the use of ammonia should be avoided, because the formation of disulfide bonds will be promoted under alkaline pH conditions. 3. Neutral or highly hydrophobic peptides, containing many polar uncharged amino acids or non-polar hydrophobic amino acids, should use a small amount of organic solvents (for example: DMF, methanol, propanol, isopropanol, DMSO) Dissolved because DMSO can form the weathered amino acid A. 4. The chaotropic agent (such as urea, guanidine hydrochloride) is sometimes used to dissolve the aggregated polypeptide, but if possible, it should not be used as much as possible, because the chaotropic agent will interfere with the biological application of the polypeptide. In some cases, the dissolution time of the peptide is longer, even up to several hours, and ultrasonication in a water bath for a few minutes can promote the dissolution of large particle peptides. But don't heat it too much. Polypeptides containing Trp, Met, Cys should be taken extra care to avoid oxidation, and should be dissolved with anaerobic water or reducing agents (such as DTT). During storage, the peptide solution should be placed at -15 ℃ after packaging, and it can be kept stable for several months. The peptides containing Trp, Met and Cys have a short half-life and should not be stored for a long time. When dissolving and storing peptides, the following points should be followed: 1. Net weight of peptide When preparing the polypeptide solution, the net weight of the polypeptide should be considered. The HPLC purity of research peptides is generally above 95%, and the solid content of peptides is in the range of 70-90%, which is due to other ions (such as acetic acid / trifluoroacetic acid) and residual moisture contained in the peptides. The peptide content of each batch is recorded on the analysis data report (you can 2. Disposal of peptide freeze-dried powder * Long-term storage of peptides should be placed below -15 ℃. * Peptides are easy to absorb moisture. You should put the bottle containing the peptide in a glassware at room temperature to equilibrate the temperature before opening the bottle to weigh the peptide. After the peptide absorbs moisture, it will affect the stability and reduce the content of the peptide. * After weighing the required amount of peptide from the bottle, the cap should be tightened immediately. 3. Dissolve in storage * Peptide should be dissolved in appropriate solution: acidic peptide should be dissolved in alkaline solution, and alkaline peptide should be dissolved in acidic solution. Use ultrasound to help dissolve when necessary. * Peptides containing Trp, Net, Cys should pay special attention to avoid oxidation. Oxygen-free water or reducing agents should be used. * When storing, the peptide solution should be placed below -15 ℃ after packaging. Most of the peptides containing Trp, Net and Cys are short-term and should not be stored for a long time. Garlic Tool,Garlic Press,Amazon Garlic Press,Garlic And Herb Tools Xiongyang Household Co., Ltd , https://www.nbyjkitchen-manage.com Website download)