Guidelines for the use of polypeptide calculators and the analysis of results
Peptide sequence input
1 sequence input
You can enter your polypeptide sequence (amino terminal → carboxyl terminal) in the box under "Sequence", the input format can be 1 or 3 characters of amino acids, or a combination of both.
2 Selection of peptide N/C terminal modifications
The aminoterminal modifications were acetylation, biotin labeling and pyroglutamate.。
Result analysis
1 Molecular weight
The molecular weight of the polypeptide can be calculated quickly by inputting the target sequence。
2 Isoelectric point
The isoelectric point is the PH of the target polypeptide at zero net charge, calculated according to the authoritative Lehninger Principles of Biochemistry.
3 The net charge at PH 7
The net charge at PH 7 refers to the net charge carried by the target polypeptide in a solution at PH 7；Of course, you can also learn the Net charge of the target polypeptide at different PH conditions based on the "net charge" chart.
4 Mean hydrophilicity
The average hydrophilicity is obtained according to the hydrophilic/hydrophobic values of each amino acid residue and different modifications in the peptide sequence.From the average hydrophilic value of a peptide, we can judge how soluble it is in water.
| The average hydrophilic value is 2 ~ 3： |
This indicated that the solubility of the polypeptide was very good. Even if the peptide is briefly in contact with air, it may absorb moisture. In order to solve this problem, a GMP level laboratory which can greatly reduce the air humidity was established, and the packaging of polypeptides was completed in this laboratory. At the same time, at the time of delivery, we will also place efficient moisture absorbent in the peptide packaging box to minimize the possibility of moisture absorption of the peptide. |
| The average hydrophilic value is 0 ~ 2： |
In general, such peptides dissolve well in water; Better dissolution effect can be obtained without adding cosolvent. |
| The average hydrophilic value is =0： |
The solubility of polypeptides in water is general; The solubility of polypeptides can be increased by the following methods: 1 Adjust the PH of the solution to help dissolve; 2 Ultrasonic dissolution aid; 3 Adjust the solution temperature (≤30℃) to help dissolve; 4 Add cosolvent (such as DMSO, DMF, etc.), it is recommended to dissolve the peptide in organic solvent first, and then slowly add water or other buffer solution. 5 For basic peptides, it is recommended to dissolve with 10% acetic acid, and for acidic peptides, it is recommended to dissolve with 10%NH4HCO3. |
| The average hydrophilic value is 0 ~ -2： |
The solubility of polypeptide in water is poor. You can use the above 5 methods to help dissolve, and you can also add hydrophilic amino acids to the peptide sequence to increase the hydrophilicity of the peptide. |
| The average hydrophilic value is -2 ~ -3: |
The solubility of polypeptides in water is very poor; As a result, the peptide is difficult to purify, and the purity of the peptide is also difficult to improve, and the customer will encounter the problem of abnormal insolubility of the peptide when using this peptide. In such cases, we usually advise customers to change the sequence or add a hydrophilic amino acid to the existing sequence. |
In addition, the solubility of the polypeptide is also related to its secondary structure, the nature of the modified marker, the type of solvent and the final concentration.
5 Proportion of hydrophilic residues
Refers to the percentage of hydrophilic amino acid residues in the total residues of the peptide sequence.