Substitution determination of Fmoc‐substituted resins at different wavelengths

Abstract

In solid‐phase peptide synthesis, the nominal batch size is calculated using the starting resin substitution and the mass of the starting resin. The starting resin substitution constitutes the basis for the calculation of a whole set of important process parameters, such as the number of amino acid derivative equivalents. For Fmoc‐substituted resins, substitution determination is often performed by suspending the Fmoc‐protected starting resin in 20% (v/v) piperidine in DMF to generate the dibenzofulvene–piperidine adduct that is quantified by ultraviolet–visible spectroscopy. The spectrometric measurement is performed at the maximum absorption wavelength of the dibenzofulvene–piperidine adduct, that is, at 301.0 nm. The recorded absorption value, the resin weight and the volume are entered into an equation derived from Lambert–Beer's law, together with the substance‐specific molar absorption coefficient at 301.0 nm, in order to calculate the nominal substitution. To our knowledge, molar absorption coefficients between 7100 l mol−1 cm−1 and 8100 l mol−1 cm−1 have been reported for the dibenzofulvene–piperidine adduct at 301.0 nm. Depending on the applied value, the nominal batch size may differ up to 14%. In this publication, a determination of the molar absorption coefficients at 301.0 and 289.8 nm is reported. Furthermore, proof is given that by measuring the absorption at 289.8 nm the impact of wavelength accuracy is reduced. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.

Efficient Method for the Concentration Determination of Fmoc Groups Incorporated in the Core-Shell Materials by Fmoc–Glycine

“…Nevertheless, the detailed research on Fmoc-substituted resin at a different wavelength determined previously (ε = 6089 dm 3 × mol −1 × cm −1 ) at 289,8 nm and (ε = 8021 dm 3 × mol −1 × cm −1 ) at 301 nm [ 76 ] encouraged us to compare different ε coefficient of dibenzofulvene–piperidine in DMF for calculation of Fmoc groups on core-shell nanostructures and model sample (Fmoc–Gly–OH).…”

“…After this time, the precipitate was left for 1 h to settle down at the bottom of the cuvette and then the absorption spectra were obtained. The estimation of the Fmoc group loading was conducted according to the equation [ 76 ]. The knowledge concerning the loading of Fmoc groups attached to NPs enables the estimation of amino groups load at the nanoparticle surface.…”

Regeneration of aged DMF for use in solid‐phase peptide synthesis

“…The DBF‐piperidine adduct has absorption maxima at around 267 nm, 290 nm, and 301 nm, with spectrophotometric determinations of resin loading generally obtained at around 290 nm and 301 nm. In the study presented, determinations were performed at 290 nm, because substitution determination at this wavelength has been recently described by Eissler et al as more reliable . The results of the comparative loading experiments are shown in Table and Figure .…”

Sustainable, Site‐Specific Linkage of Antimicrobial Peptides to Cotton Textiles

“…From the UV absorption of this solution we quantified the dibenzofulvene‐piperidine adduct (ε = 6089 cm −1 mol −1 at 298.8 nm) release upon Fmoc cleavage. [ 31 ] Based on the weight of the starting cotton, we estimated the peptide loadings on the cotton (Table 1).…”