Sulfinamide signals on WT-PLN and its variants. (a–c) Selected region of ¹⁵N-edited ¹H 2D-NMR spectra showing C41,46A-PLN (a; 60 µM, single Cys at position 36), C36,46A-PLN (b; 60 µM, single Cys at position 41; red), and C36,41A-PLN (c; 60 µM, single Cys at position 46; blue) upon treatment with the H¹⁵NO donor, ¹⁵N-2-MSPA (1 mM) in phosphate buffer containing DPC (pH 7.4) at 37°C for 30 min. (d) Overlay of H¹⁵NO-derived sulfinamide signals. (e–g) Selected region of ¹⁵N-edited ¹H 1D-NMR spectra showing C41,46A-PLN (e; 60 µM, single Cys at position 36), C36,46A-PLN (f; 60 µM, single Cys at position 41), and C36,41A-PLN (g; 60 µM, single Cys at position 46) upon treatment with the H¹⁵NO donor, ¹⁵N-2-MSPA (1 mM) in phosphate buffer containing DPC (pH 7.4) at 37°C for 30 min. (h–j) Selected region of ¹⁵N-edited ¹H 2D-NMR spectra showing C36A-PLN (h; 60 µM, Cys at positions 41 and 46; green), C46A-PLN (i; 60 µM, Cys at positions 36 and 41; blue), and WT-PLN (j; 60 µM; red) upon treatment with the H¹⁵NO donor, ¹⁵N-2-MSPA (1 mM) in phosphate buffer containing DPC (pH 7.4) at 37°C for 30 min. (k) Overlay of H¹⁵NO-derived sulfinamide signals. (l–n) Selected region of ¹⁵N-edited ¹H 1D-NMR spectra showing C36A-PLN (l; 60 µM, Cys at positions 41 and 46), C46A-PLN (m; 60 µM, Cys at positions 36 and 41), and WT-PLN (n; 60 µM) upon treatment with the H¹⁵NO donor, ¹⁵N-2-MSPA (1 mM) in phosphate buffer containing DPC (pH 7.4) at 37°C for 30 min.