A protected spin-labelled, cyclic, chiral ?amino acid resolved in an enantiomerically pure state
Fmoc-2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic Acid is a stable, free radical spin label.
A stable free radical spin label.
Fmoc-TOAC-OH is a useful tool for the incorporation of the ESR spin-label TOAC into peptide sequences [1]. Incorporation of this derivative and the following residue is best achieved using HATU activation. TFA/water/TIS should be used for cleavage of TOAC-containing peptides. The use of EDT should be avoided as it can cause permanent reduction of the nitroxide radical [2]. Following cleavage, the TOAC peptide should be treated with aqueous ammonia in air to regenerate the nitroxide from the hydroxylamine that is generated by the TFA treatment.
