Fmoc-8-amino-3,6-dioxaoctanoic acid

Fmoc-8-amino-3,6-dioxaoctanoic acid
Fmoc-AEEA, Fmoc-NH-PEG2-CH2COOH; 2-[2-[2-(9H-fluoren-9-ylmethoxycarbonylamino)ethoxy]ethoxy]acetic acid

This is not an amino acid. There is no α-carbon, no side chain and no stereocentre: it is a short ethylene-glycol chain with an Fmoc-protected amine at one end and a free carboxylic acid at the other. Those termini allow it to be coupled and Fmoc-deprotected in the corresponding peptide-synthesis cycle and placed at internal or terminal positions in compatible constructs.

What it contributes: between the amide nitrogen it brings and its own carbonyl carbon there are seven atoms — CH2CH2-O-CH2CH2-O-CH2 — two of them ether oxygens, with no substituents along the way. The carboxyl end is an alkoxyacetic acid, the carbon next to the carbonyl carrying one of those oxygens. Several can be coupled in series to lengthen the spacer; the next one up in this catalogue, Fmoc-12-amino-4,7,10-trioxadodecanoic acid (47261), contributes eleven atoms and three oxygens instead.

What a spacer of this length does in a given construct is something to measure in that construct. What can be said here is structural: there is no stereocentre to epimerise on activation, and no side-chain protecting group to come off at cleavage.

Applications

• Flexible spacer between a peptide and a label, biotin, chelator or other cargo
• Separating two peptide segments, or a peptide from a resin-bound scaffold
• Spacer series in which the length is varied one unit at a time

Storage
Store refrigerated (2–8 °C) in a tightly closed container, and let it reach room temperature before opening.

For research use only. Not for human or veterinary use.