常见问题解答

• 如何进行询价？
目录肽或定制肽询价，请点击这里提交信息，或者通过邮件（sales@biopeptek.cn）、电话（0532-55676230）、传真（0532-55676180）联系我们。请提供以下信息：
• 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
• 如何在双元泰和下订单？
订单下单请通过邮箱(info@biopeptek.cn)、电话(0532-55676230)，传真(0532-55676180)将您的订单信息提供给我们。您也可以通过www.biopeptek.cn在线提交。
• 双元泰和的多肽提供哪些检测报告？
我们提供所有多肽的质谱报告，对于有纯度要求的多肽，我们提供RP-HPLC和COA报告。COA报告包含产品的颜色、性状、质量等信息。
• 双元泰和的产品交货期是多久？
常规多肽交货期2-3周，根据多肽的长度和难度时间有所不同。我们会根据您的项目要求及时更新周期和进度。
• 我的项目应该选择多少纯度的多肽？
常用多肽纯度如下：
1. 多肽纯度 >85%: 免疫、多克隆抗体、非敏感筛选。
2. 多肽纯度 >90%: 结构-活性关心研究和生物活性测定。
3. 多肽纯度 >95%: ELISA、酶学、生物活性研究
4. 多肽纯度 >98%: 结构研究/晶体学，NMR和敏感生物测定。
• 多肽纯度和多肽含量的区别？
多肽纯度是使用面积归一HPLC法，测定多肽在214nm的UV吸光度来测定多肽纯度的方法。因为水分和盐分在214nm没有吸收，该方法测定的多肽纯度不包含多肽水分和TFA盐等。
如果多肽没有盐分要求，双元泰和提供的多肽包含水和少量的TFA盐。醋酸盐、盐酸盐多肽可以根据客户要求提供。
多肽含量是指样品中多肽类物质的含量，通常情况下合成多肽含量从70%到90%，在某些情况下，多肽含量可能低于30%。
• 双元泰和是如何生产多肽的？
双元泰和多肽使用SPPS和LPPS方法进行合成。整个流程符合cGMP规范，下图是我们质量控制流程：



• 非HPLC纯化的多肽中有哪些杂质?
粗品和脱盐级别的多肽中多肽和非多肽类杂质：如非全长多肽和多肽后处理的一些原料如DTT、TFA等。

经过HPLC纯化的多肽，仍会有一些一些杂质存在，其中的杂质主要是短肽和微量TFA。

• 冻干多肽如何保存？
• 储存多肽的瓶盖应该盖紧，根据实验计划将多肽分装成小包装。
• 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℃。
• 对于冻干多肽和多肽溶液应该避免反复冻融，如果样品要频繁使用，建议将样品分装成小包装。
• 多肽序列中含有C、M、W容易空气氧化，建议抽真空或者使用惰性气体保护。
• 通常多肽溶液在-4℃可以稳定储存一周，如果多肽序列中含有不稳定氨基酸或者结构，不建议液体保存。不建议多肽在PH>8的溶液中保存。
• 多肽如何溶解？
溶解多肽是非常复杂的事情，一般很难一下子确定合适的溶剂。通常是先取一点试验，在没有确定合适的溶剂前千万不要全部溶解。下列方法有助于您选择合适的溶剂：
• (1)判定多肽的电荷特定，设定酸性氨基酸Asp(D),Glu(E)和C端COOH为-1；碱性氨基酸Lys(K),Arg(R),His(H)及N端NH2为+1,其它氨基酸的电荷为0。计算出将电荷数。
• (2)如果净电荷数>0，多肽为碱性，用水溶解：如果不溶解或溶解性较小，加入醋酸(10%以上)；如果多肽还不能溶解，加入少量TFA(25ul)溶解，然后加入500ul水稀释。
• (3)如果净电荷数<0，多肽为酸性，用水溶解；如果不溶解或溶解性不大，加入氨水(25ul)溶解，然后加入500ul水稀释
• (4)如果净电荷数=0，多肽呈中性，一般需要用有机溶剂如乙腈，甲醇或异丙醇，DMSO等溶解。还有人建议需要尿素来溶解疏水性很大的多肽。
• 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.