Shiftcor

Shiftcor corrects and re-references ^1H, ^13C, and ^15N backbone chemical shifts of peptides and proteins by comparing observed NMR shifts to SHIFTX-predicted shifts from three-dimensional structural coordinates (PDB) to identify and rectify mis-assignments and referencing errors.

Key Features:

• Chemical Shift Comparison: Compares observed ^1H, ^13C, and ^15N backbone chemical shifts with SHIFTX predictions generated from PDB three-dimensional coordinates.
• Error Identification and Correction: Applies statistical evaluations to identify mis-assignments, typographical errors, and chemical referencing errors and enables retrospective correction.
• Unbiased Re-Referencing: Performs instrument-independent re-referencing and applies IUPAC conventions for ^13C and ^15N referencing.
• Integration with RefDB: Integrates with RefDB, a database of reference-corrected protein chemical shifts, to link corrected records.
• BMRB Error Mitigation: Targets prevalent referencing errors present in BioMagResBank (BMRB) protein entries to improve data consistency.

Scientific Applications:

• Structural model validation: Improves the reliability of NMR-derived protein structural models by correcting chemical shift referencing.
• Data curation and standardization: Enables re-referencing of published protein chemical shifts for accurate deposition in BMRB and RefDB.
• Assignment validation: Aids detection and correction of backbone resonance mis-assignments and typographical errors in NMR datasets.

Methodology:

Predicts chemical shifts using SHIFTX from 3D structural coordinates (PDB); compares predicted shifts with observed NMR shifts to identify discrepancies; applies statistical methods to evaluate and correct mis-assignments, typographical errors, and referencing errors; and re-references chemical shifts according to IUPAC standards for ^13C and ^15N.