- 目录肽: 目录肽编号和重量
- 定制多肽: 多肽序列、修饰、质量、纯度(Desalted, >75%, >80%, >90%, >95%, >98%)等
- 多肽纯度 >85%: 免疫、多克隆抗体、非敏感筛选。
- 多肽纯度 >90%: 结构-活性关心研究和生物活性测定。
- 多肽纯度 >95%: ELISA、酶学、生物活性研究
- 多肽纯度 >98%: 结构研究/晶体学，NMR和敏感生物测定。
- 多肽短期储存 (三个月以内) 应该储存在-20℃，更长期的储存，我们推荐-80℃。
- How do I estimate the net charge of my peptide?
The steps outlined below provide you with a method for determining the best solvent for a synthetic peptide based on its amino acid sequence. It is best to first solubilize a small aliquot of the sample, rather than the entire stock.
- Assign a value of -1 to each acidic residue. The acidic residues are Asp (D), Glu (E), and the C-terminal -COOH.
Assign a value of +1 to each basic residue. The basic residues are Arg (R), Lys (K), His (H), and the N-terminal -NH2.
- Calculate the overall charge of the synthetic peptide.
- If the overall charge of the synthetic peptide is a positive value, you have a basic custom peptides. Initially try to dissolve the peptide in water. If the peptide does not dissolve, try 10% and higher solutions of acetic acid. If the peptide still does not dissolve, add TFA (<50?L) to solubilize the peptide and dilute to 1mL with deionized water.
- If the overall charge of the peptide is a negative value, you have an acidic peptide. Initially try to dissolve the peptide in water. If the custom peptides does not dissolve, add NH4OH (<50?L) and dilute to 1ml with deionized water.
- If the overall charge of the synthetic peptide is zero, your custom peptides is considered neutral. Neutral peptides may require the addition of organic solvents, such as acetonitrile, methanol, or isopropanol. The addition of denaturants, such as urea or guanidinium-HCL may also be necessary.
- If my peptide has a purity of 90%, what are the other 10%?
If a synthetic peptide has a purity of 90%, the other 10% contains synthetic peptides that have shorter sequences, truncated sequences, sequences with incomplete deprotectionly deprotected sequences
- Peptide sequences modified during cleavage (reattachment of protecting groups at other locations on the synthetic peptide)
- Synthetic peptides that have undergone side reactions
- How do I design my peptide?
The steps outlined below provide you with a method for a good idea to choose the terminal ends of the custom peptide dependent on the natural occurrence of the peptide sequence:
- The custom peptide should mimic an internal sequence of a protein. The peptide should not be charged at the ends. The N-terminus of the custom peptide should be acetylated and the C-terminus should be amidated.
- If the synthetic peptide sequence is the C-terminal end of a protein, the C-terminus should be the free acid and the N-terminus should be acetylated.
- If the synthetic peptide sequence is the N-terminal end of a protein, the C-terminus should be an amidated and the N-terminus should be in the natural free amine form.
- If the custom peptide is for cytotoxic T-cell epitope studies, a free amino group at the N-terminus and a free acid at the C-terminus are necessary. These ends are the natural equivalents to the synthetic peptide fragments, processed intracellularly from whole proteins.
- If the custom peptide is for antibody production, please check the technical resources section of our website.
- What are the characteristics of carrier protein KLH vs. BSA?
Both KLH and BSA are common carrier proteins which are long peptides. The molecular weight of BSA is much smaller than KLH. However, BSA is much more soluble and immunogenic. It contains 59 lysines, 30-35 as primary amines capable of reacting with conjugation sites of linkers. It is a popular carrier for weakly antigenic compounds. BSA can be used to block nonspecific binding sites in many immunochemical experiments such as ELISA, immunoblotting and immunohistochemical studies. It may be used as a non-relevant protein in enzyme immunoassays.
The KLH cannot be used for this because the anti-KLH antibodies, which formed during immunization, will interfere with the measurement of anti-heptan antibodies. When KLH is used as the carrier, heptan-BSA conjugates can be used because they do not interfere with the measurement for anti-heptan antibodies.
- What is the length of the peptides Biopeptek can synthesize?
Biopeptek routinely peptide synthesis
of 3 - 50 amino acids in length. We can also synthesize peptides of greater than 100 amino acids in length. The minimum length of synthetic peptides should not be less than 3 amino acids. For shorter custom peptide
sequences, cleavage from the synthesis resin and following purification can be problematic.
- Do I need Amino Acid Sequencing?
Solid phase peptide synthesis is carried out under a controlled and calculated environment. There are very few occasions that the synthetic peptide sequence is in question. By using a mass spec analysis, you can determine the molecular weight of the synthetic peptide, thus proving the sequence completion of the peptide synthesis. However, there are cases where peptide sequencing is something we recommend, such as with MAPS peptides. With the majority of MAPS peptides, the mass spec analysis provides inconclusive information, because of the nature of MAPS peptides. Sequencing can be an easy alternative for proof of peptide synthesis completion, and affirmation of peptide sequence in publication use.
- What is PEGylation and how do I use it?
Polyethylene glycol (PEG) is a useful delivery system for custom peptide and protein-based biopharmaceuticals. PEGylation is the chemical attachment of PEG to a custom peptide on a specified site of the molecule. Studies have shown an increase in the potential bioavailability of custom peptides when incorporating PEG into synthetic peptide sequences versus the injection of a naked peptide. Drug oriented custom peptides show significant improvement to their therapeutic properties, including better patient compliance and side effect profile.