Fig. 7.

Upper left Schematic illustration of possible magnetization transfers via J(C,C) or J(C,P) couplings. a assigned 2D (H)CPC spectrum of the 14mer RNA. b assigned 2D (H)CP-CC-TOCSY-C1′ spectrum with a long CC-mixing time of τ_M = 32 ms for magnetization transfer to C1′. C: assigned 2D (H)CPC-C5′ spectrum with an additional transfer-step to C5′. All experiments were recorded on a 600 MHz NMR spectrometer and a temperature of 298 K using a cryogenic probe for ¹H, ¹³C and ³¹P. The field strengths for ¹H, ¹³C and ³¹P pulses were 23.8, 16.8 and 12.5 kHz, respectively. During acquisition, WALTZ and GARP decoupling sequences were applied at field strengths of 3.6 kHz and 833 Hz for ¹H and ³¹P, respectively. The FLOPSY sequence was applied at a field strength of 8.3 kHz. The (H)CPC experiment was recorded with 512 scans for a period of 15 h. The (H)CP-CC-TOCSY-C1′ experiment was recorded with 1,792 scans for 52 h and the total experimental time for the (H)CPC-C5′ was 25 h. All three experiments were recorded with 20 and 1 k complex points in t₁ and t₂ by using a relaxation delay of 1 s. The acquisition time was set to 135 ms and t^max₁ was 24 ms for all three experiments