GFT Spectra Parameters in CARA

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GFT Spins in Residue Definitions

I had to modify the residue definitions to get GFT spins displayed for (4,3)D HCCH-COSY spectra in SystemScope. Sum and difference "spins", such as !CBmHB3, were added and linked in Molecule Viewer.

For information on how to edit residue type definitions see this page: http://www.cara.ethz.ch/Wiki/ResidueType

GFT Spectra

In general, GFT spectra can be loaded just like any other spectra.

(4,3)D GFT Triple-Resonance Spectra

The current template for GFT based Main.HTP protocol contains spectrum type definitions for (4,3)D CABCA(CO)NHN, (4,3)D HNNCABCA, (4,3)D HACA(CO)NHN and (4,3)D HABCAB(CO)NHN. They are separate definitions for "sum" and "difference" subspectra, denoted by "p" and "m" respectively. For example, spectrum type GFT_HNCABCAp corresponds to the "sum" subspectrum of (4,3)D HNNCABCA. This entry declares that allowed labels in the 13C dimension are intra- and sequential !CApCA and !CApCB.

   

  • Example of GFT spectrum definition:
          CARA gft spectrum types.png

(4,3)D HCCH spectra

Central peak and basic subspectra of aliphatic and aromatic HCCH-COSY should all be loaded as conventional 3D aliphatic and aromatic 3D (H)CCH-COSY spectra.

GFT-Specific Attributes

Lua macros dealing with chemical shift combinations require certain GFT-specific attributes to work properly. Right-click on the particular spectrum tab, and select Edit Attributes... from the context menu.

   

  • Edit attributes of a spectrum:
          CARA spectrum edit attr.png

The Edit Attributes dialog window will pop up, where you should set the following attributes for a (4,3)D experiment:

   

  • check the GFT box 
  • set the number of GFT dimensions (GFTDimNumber) to 1
  • set the number of projected dimensions (GFT1ProjNum) to 1
  • set the spin type of the first projected dimension (GFT1ProjSpinType1) to
    • C - for CABCA(CO)NHN and HNNCABCA
    • H - HACA(CO)NHN and HABCAB(CO)NHN and HCCH
  • set the carrier offset of the first projected dimension (GFT1ProjCarrier1) in ppm
  • Set GFT-specific attributes:
          CARA gft edit attr.png

The attributes are somewhat superfluous, and some may only be needed in future script developments.

-- Main.AlexEletski - 07 Mar 2007

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