Carbon-detected NMR Experiments

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With the advent of high-sensitivity probeheads, 2D ¹³C-detected and 3D ¹³C-detected experiments have become attractive tools to be applied in special cases, as for instance, in large deuterated proteins or in paramagnetic proteins ( 04JACS10496 ) showing fast relaxing properties. For a complete revision article see 06PROG25-48 .

2D 13C{13C} COSY 2D 13C-13C TOCSY 2D 13C{13C} NOESY 2D CACO 2D CO-N 2D CA-N

3D CANCO 3D HCC-TOCSY 3D HACACO 2D/3D CBCACO ( 05ANG3089 ) 2D & 3D CCCO ( 05JMR404-177 ) 3D CCCON ( 05JMR404-177 ) 3D CBCANCO 3D CBCACON ( 05JMR404-177 )

Advantages of 13C detection:

• Enables to work at a very high level of proton dilutions. Interesting for large deuterated proteins.
• Better resolution on the acquired dimension.
• The overall length of the pulse sequences can be shortened. Interesting for fast relaxing systems such as paramagnetic proteins or flexible proteins.
• The requirements for solvent suppression during acquisition are avoided.
• Improved sensitivity and resolution with the possible use of deconvolution using maximum Entropy (MaxEnt) resonstruction to eliminate the CC splitting in the final spectra.
• ACquisition can be started with anti-phase coherence, resulting in higher sensitivity due to the elimination of the final INEPT transfer step ( 04JB175-30 )

Disadvantages of ¹³C detection:

• The sensitivity of a NMR pulse scheme depends of gamma(exp(3/2)). Thus, in the case of 13C, proton-detection is 8 times more sensitive than ¹³C-detection.