A4 Amyloid Beta [Asn670,Leu671]-APP770 (667-676)

1 Identity

Linear synthetic decapeptide, all-L, free acid. A fragment of the amyloid precursor protein spanning the beta-secretase cleavage site, carrying the Swedish (Lys-Met to Asn-Leu) familial mutation. It is an enzyme assay substrate. which is a trade name and not an identity. and "SEVNLDAEFR"; sold in at least three independent sellers' catalogs as "A4 Amyloid beta 0.5MG". which is the correct systematic name.

Sequence

H-Ser-Glu-Val-Asn-Leu-Asp-Ala-Glu-Phe-Arg-OH (SEVNLDAEFR). Wild-type is SEVKMDAEFR; this article is the Swedish variant and the two differ at positions 4 and 5.

Molecular formula

C50H78N14O19

Average mass

1179.253 Da for C50H78N14O19.

Monoisotopic mass

1178.55677 Da for the neutral molecule; [M+H]+ 1179.56405. Wild-type SEVKMDAEFR is 16 Da heavier and a unit-resolution instrument will not reliably separate them.

Salt / variant note

(1) Amyloid beta 1-40, 4329.8 Da, and amyloid beta 1-42, 4514.1 Da — the aggregating species this article is named after and is not. (2) The A4/APP precursor protein itself, approximately 110 kDa. "A4" is an archaic but legitimate synonym for the precursor, which is precisely why the product name misleads: it names the 110 kDa parent while the vial holds a 1.2 kDa fragment of it. (3) Wild-type SEVKMDAEFR, 1195.3 Da — only 16 Da from this article, and cleaved by BACE1 at a markedly different rate, so substituting one for the other silently changes the kinetics.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

The identity is over-determined and therefore secure: the CAS number, the printed molecular formula and the mass calculated from that formula agree with each other and with an institutional supplier's listing. Three concordant identifiers against one incorrect prose description. Where a seller's specification and its marketing copy disagree, this company records the specification and says the copy is wrong.

4 Storage & specification

Storage

Lyophilized powder, stored at -20 degrees C plus or minus 5 degrees C, desiccated and protected from light. Reconstituted aliquots are single-use.

Shelf life

Provisional 24 months at -20 degrees C, assigned by protocol and not by measured stability.