看到Amyloid β-Protein，第一反應就是和阿爾茨海默氏病有關，這類研究的相關肽種類已經(jīng)有接近200種了，包括各種缺失肽，某位置氨基酸被替換的肽段（簡稱替換肽），局部片段肽，含有Met(O)、Met(O2)等雜質(zhì)肽，生物素FITC等標記肽，等等。

Amyloid β-Protein的相關序列，我們通常稱之為淀粉肽，因為大部分長肽片段的性質(zhì)比較疏水，在溶液中可能發(fā)生聚集沉淀，就像淀粉一樣，很難溶解，故稱之為淀粉肽。

今天介紹其中一種淀粉肽片段，Amyloid β-Protein (1-40)，

其它寫法有β-Amyloid (1-40), Aβ40

CAS號：131438-79-4

單字母：DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVV

三字母：Asp-Ala-Glu-Phe-Arg-His-Asp-Ser-Gly-Tyr-Glu-Val-His-His-Gln-Lys-Leu-Val-Phe-Phe-Ala-Glu-Asp-Val-Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-Val-Gly-Gly-Val-Val

氨基酸個數(shù)：40

分子式：C194H295N53O58S1

平均分子量：4329.8034

精確分子量：4327.1481475

等電點(PI)：6.3

pH=7.0時的凈電荷數(shù)：-1.42

平均親水性：-0.1

疏水性值：:0.06

結構如下圖：

描述：

Compared to the TFA salt, the HCl salt of amyloid β-protein (1-40) easily forms β-structures in PBS within a few hours at 25°C. β-structure formation is essential for amyloid peptide toxicity.

Amyloid β-peptide (1-40) showed both neurotrophic and neurotoxic effects in dependence on the neuronal age and the concentration of the β-protein. Aβ 1-40 has been used as well as Aβ 1-42 to detect amyloid β-protein multimers in the cerebrospinal fluid of Alzheimer's disease patients. The sequence of this peptide corresponds to the sequence of human, bovine, canine, feline, ovine, guinea pig, and rabbit Aβ40. The inverted sequence can be used as inactive control in experiments employing Aβ 1-40. For detailed descriptions of the preparation of wild-type and mutant Aβ 1-40 monomers and protofibrils please see the paper of Jan, Hartley, and Lashuel.

文獻：

1、http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15998280

2、http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=27000658

3、http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=26919121

4、http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=27665848

5、https://www.ncbi.nlm.nih.gov/pubmed/27608011

6、https://www.ncbi.nlm.nih.gov/pubmed/26632651