{"id":2896,"date":"2026-10-03T15:53:03","date_gmt":"2026-10-03T15:53:03","guid":{"rendered":"https:\/\/nhdbio.com\/?p=2896"},"modified":"2026-10-03T16:04:14","modified_gmt":"2026-10-03T16:04:14","slug":"%e8%82%bd%e6%9c%ab%e7%ab%af%e4%b9%99%e9%85%b0%e5%8c%96%e4%b8%8e%e9%85%b0%e8%83%ba%e5%8c%96%e7%9a%84%e9%a1%ba%e5%ba%8f%e8%a7%84%e8%8c%83","status":"publish","type":"post","link":"https:\/\/nhdbio.com\/cn\/peptide-terminal-acetylation-amidation-order-specification\/","title":{"rendered":"Custom peptides: don't just write the sequence \u2014 spell out how both ends are handled too"},"content":{"rendered":"

You have the amino-acid sequence ready. Is that enough for a peptide quote? Not always. The two ends of the chain can have different chemical groups, even when every amino acid in the middle stays the same. A supplier needs to know which version you want.<\/p>\n

Think of the ends as part of the design<\/h2>\n

The beginning is called the N-terminus; the other end is the C-terminus. In Bachem\u2019s notation, H- indicates a free amino end, Ac- indicates an acetylated end, -OH indicates the unmodified acid end and -NH2 indicates an amide end. These symbols carry information that a short sequence alone may leave out. [1]<\/p>\n

One short sequence, four possible descriptions<\/h2>\n

Here is an invented ordering example using Ala\u2013Gly\u2013Lys. If the only choices are a free or acetylated N-end and an acid or amide C-end, there are 2 \u00d7 2 = 4 combinations. H-Ala-Gly-Lys-OH, Ac-Ala-Gly-Lys-OH, H-Ala-Gly-Lys-NH2 and Ac-Ala-Gly-Lys-NH2 are therefore four different specifications. This count does not say they behave alike or are all suitable for your work.<\/p>\n

Acetylation is not a quality upgrade<\/h2>\n

A modified end changes the molecule. It is not simply a more premium version of the same material. If you are following a paper, copy its full structure and terminal notation. If the method is unclear, resolve that question before ordering. Do not choose a modification only because it sounds more stable.<\/p>\n

Check the calculator as well as the quote<\/h2>\n

A molecular-weight calculation must describe the final molecule, including its ends. A calculator set to free termini can give a different result from one set to acetylation and amidation. Keep those settings with the calculated value so that you can check them against the supplier\u2019s specification.<\/p>\n

What to include in your enquiry<\/h2>\n

Send the sequence from N to C, mark both terminal groups, and list any side-chain changes separately. If you need two versions for comparison, give them separate identifiers and ask for separate prices. NHD\u2019s custom synthesis enquiry is a starting point; the requested chemistry and analytical records still need confirmation.<\/p>\n

Useful links<\/h2>\n