网址：www.prottech.com.cn

由于蛋白质翻译后细胞内的修饰和处理，一个蛋白质的N-和C-端通常不能根据基因序列预测， 而且，在生物产品中一种蛋白质产物中可能还会出现不同的N-或C-端。因此，分析鉴定蛋白产物N- 和C-端是生物制品必不可少的。

ProtTech提供两种测定蛋白质产品N-和C-端的服务。1）结合肽图谱， 通过MS/MS检测出蛋白质N-端和C-末端并且可以测出它的序列，这项技术可以测出封闭的或修饰的蛋白质末端， 也可以测出一种蛋白质的不同种类的C-端或N-端。我们也可以用Edman化学方法检测报告蛋白质N-端的氨基酸。 目前还没有成熟的蛋白质C-末端的化学测序方法。在这种情况下，如果肽图谱方法不能确定蛋白质的C-端， 我们可以使用的O-18标记方法，明确鉴别和测出蛋白C-末端的序列。

We currently don’t offer the Edman N-terminal sequencing service. We do offer LC-MS/MS based N-terminal sequencing in the cases that Edman sequencing doesn’t work, for example, when a protein has a capped N-terminal, or is a mixture of multiple N-terminals due to proteolytic cleavage. We also provide C-terminal sequencing based on similar technology.

LC-MS/MS can’t specifically select N-terminal peptide (with 2-3 different digestions). Basically we have to get every peptide from a protein digest in order to get the N- or C- terminal (with 2-3 different digestions). So it will take much larger effort to sequence N-terminals by LC-MS/MS than that by Edman sequencing.We’ll use LC-ESI-MS/MS based peptide mapping to confirm 100% amino acid sequence of protein samples.