It is subject to your protein's behavior. It needs in-person guidance for experiments set up. Recently, Prof. Chin-Ju Park's group did a CPMG with the help of Dr. Hae-Kap Cheong at KBSI. This paper will be helpful for you to understand basics. https://www.nature.com/articles/s42003-024-07133-1

Woonghee Lee Thank you for your response. I’ll read through the papers you shared and study them further.

To perform a CPMG (Carr-Purcell-Meiboom-Gill) experiment for T₂ relaxation measurements in Bruker TopSpin, begin by loading the pulse sequence either by typing "edcpmg" in the command line or manually selecting it from the sequence library. Before acquisition, several critical parameters must be set: configure the time domain (TD) for sufficient digital resolution (typically 32k points), set the number of scans (NS) between 4-16 for adequate signal-to-noise, and ensure the relaxation delay (D1) is at least five times the expected T₁. The CPMG-specific parameters require particular attention - carefully calibrate the 90° pulse width (P1) using the "pulsec" command and set the 180° pulse width (P2) to exactly twice this value. The echo time (D20), representing 2τ, should be initially set between 200 μs to 1 ms based on your sample's expected T₂, while the number of echoes (NECH) typically ranges from 100-1000 to fully capture the relaxation decay. Always optimize the receiver gain using the "rga" command before starting acquisition with "zg". During processing, apply Fourier transformation ("efp" or manual "ft"), followed by phase correction ("apk" for automatic or manual adjustment). For T₂ analysis, export peak intensities versus echo times and fit to an exponential decay model, either using TopSpin's built-in tools or external software for more complex multi-exponential systems. Common issues to watch for include signal strength (addressable by increasing NS or rechecking pulse calibrations), artifacts from improper echo times, and baseline drift (correctable with exponential line broadening). For advanced applications involving multi-exponential decays, consider using inverse Laplace transform methods available in specialized software packages. Throughout the process, remember that CPMG experiments are particularly sensitive to pulse calibration accuracy, making regular verification of P1 and P2 values essential for reliable results. The entire workflow can be streamlined by creating a standardized acquisition protocol with optimized parameters for your specific sample type and spectrometer configuration.