Advance 3 600 mhz spectrometer

¹H-¹⁵N-HSQC spectra of ¹⁵N-labeled samples were recorded in 50 mM Tris pH 7.4, 150 mM NaCl, 200 μM ZnCl₂, 1 mM DTT, 10% D₂O at 25 °C with a Bruker 600 MHz Advance III spectrometer equipped with a TCI CryoProbe (Unitat de RMN, Universitat de Barcelona). NMR spectra were processed using Bruker TopSpin 3.0 and analyzed using CcpNmr48 (link). Combined chemical shift differences were calculated using the following equation:
CSP =  in which α is 0.14, but 0.2 for Gly49 (link). For backbone assignment of ¹³C¹⁵N-RNF125^{start31/stop129} in 50 mM Tris pH 7.0, 50 mM NaCl, 200 μM ZnCl₂, 1 mM DTT, a set of standard triple resonance experiments for the sequential assignment was recorded using incremental non-uniform sampling50 (link) on Bruker 800 MHz Avance III HD spectrometer equipped with 5 mm TCI CryoProbe (Swedish NMR Centre) at 25 °C. For ¹³C¹⁵N-UbcH5a assignment in 50 mM Tris pH 7.0, 150 mM NaCl, 200 μM ZnCl₂, 1 mM DTT, recording was performed with a Bruker 900 MHz Avance III HD spectrometer equipped with 5 mm TCI CryoProbe (Swedish NMR Centre) at 25 °C. Spectra were processed using MDDNMR51 (link) and the analysis was performed in CcpNmr Analysis.

A total of 5 wt% raw curdlan powder was dissolved in 0.4 wt% and 2 wt% NaOH aqueous solution, respectively, then loaded in 5 mm NMR tubes and measured using a Bruker 600 MHz Advance III spectrometer equipped with a BBO probe. Chopped small pieces of dry S gel or C gel (~3 mg) were first placed into a 4 mm HR-MAS zirconia rotor and weighed; then, 15 times the weight of water was added and the sample was sealed in the rotor for one day to maintain equilibrium swelling. The ¹³C high-resolution MAS (HRMAS) NMR experiments were performed on a Bruker 600 MHz Advance III spectrometer equipped with a 4 mm HR-MAS probe at spinning rate of 3 kHz. The temperature was controlled by a Bruker cooling unit with an accuracy of 0.1 °C. A 15 min equilibrium time was required for each NMR experiment to maintain the temperature balance.

An SMP3 melting point equipment was used to determine melting points. The ¹H NMR spectra (400 MHz) were obtained at Ain Shams University in Cairo, Egypt, using a Bruker Advance (III)-400 MHz Spectrometer. The ¹³C NMR spectra (125 MHz) were collected using a Bruker Advance (III)-600 MHz Spectrometer at Helwan University's Central Laboratory, Hub of Creativity and Scientific Research. Some spectra were set on the APT system which produces positive methene (CH) and methyl (CH₃) signals (odd) and negative (even) signals along with solvent signals. The solvent used for NMR experiments was DMSO-d₆, with Si(CH₃)₄ serving as the internal standard. Chemical shifts are recorded in parts per million (ppm), and all coupling constants (J values) are given in Hertz. The following acronyms are used in NMR analysis: “s” for singlet, “d” for doublet, and “m” for multiplet. The progress of reactions and the analysis of product mixtures were monitored on a regular basis using thin layer chromatography (TLC) on silica gel pre-coated F254 plates Merck, and using UV lamp.
Because certain compounds exhibited low solubility in DMSO-d₆, their ¹³C NMR spectra were not recorded.