Efficient Building Blocks for Solid-Phase Peptide Synthesis of Spin Labeled Peptides for Electron Paramagnetic Resonance and Dynamic Nuclear Polarization Applications.

Specific spin labeling allows the site-selective investigation of biomolecules by EPR and DNP enhanced NMR spectroscopy. A novel spin labeling strategy for commercially available Fmoc-amino acids is developed. In this approach, the PROXYL spin label is covalently attached to the hydroxyl side chain of three amino acids hydroxyproline (Hyp), serine (Ser) and tyrosine (Tyr) by a simple three-step synthesis route.

Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.

The colligative property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (CE) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated CE as well as reverse micelles are significantly present for the entire range of measured CE concentration (0.048-2.