J-Multiplied HSQC (MJ-HSQC): A New Method for Measuring3J(HNHα) Couplings in15N-labeled Proteins

J-Modulated TROSY Experiment Extends the Limits of Homonuclear Coupling Measurements for Larger Proteins

“…1), is basically a simple extension of the sensitivity enhanced, H α -decoupled TROSY (35-38) experiment discussed above (39)(40)(41)(42)(43). After the TROSY sequence, an extra J -modulation spin-echo period is incorporated, as described recently for the J -multiplied HSQC (MJ-HSQC) (44) and HMQC (MJ-HMQC) (50) experiments. The synchronous incrementation of the homonuclear Jmodulation and 15 N chemical shift evolution period, together with an appropriate scaling factor (n) for multiplying the effect 15 N SQC with coherence order +1, G4 acts on heteronuclear MQC with coherence order −1 and +1 on 15 N and 1 H, respectively, and G6 acts on 1 H SQC with coherence order −1.…”

Cosine Modulated HSQC: A Rapid Determination of 3JHNHα Scalar Couplings in 15N-labeled Proteins

“…The most widely used method for 15 N-labeled proteins is the three-dimensional quantitative-J experiment in which the ratio of cross to diagonal peaks is directly related via a tangent function to the scalar coupling (5)(6)(7). Couplings can also be obtained from multiplet splittings as in J -modulated HMQC (8) or from two-dimensional spectra in J -modulated HSQC (9), S 3 E, and S 3 CT (10) that require a transfer of 1 H magnetization via NOESY or TOCSY, J -multiplied HSQC (11), CT-HMQC-HA/HN (12,13), and CT-HSQC-HA/HN (13). In these last methods, a pair of twodimensional spectra are recorded with and without selective decoupling of the targeted scalar coupling evolution.…”

Methods for the Measurement of 1JNCα and 2JNCα from a Simplified 2D 13Cα-Coupled 15N SE–HSQC Spectrum

“…Therefore, our aim has been to develop methods allowing the direct measurement of the desired couplings from the two-dimensional 15 (14,(17)(18)(19)(20)(21)(22).…”

“…1A (and Fig. 1B as well) with an additional evolution step for the multiplication of 1 J NC␣ and 2 J NC␣ (17,18,28,29). The pulse sequence with the J-multiplication period is presented in Fig.…”