Shift-T

Shift-T analyzes variable-temperature solution NMR isotropic chemical shift data to quantify temperature-dependent amide proton and nitrogen chemical shift changes for probing hydrogen bonding, loss of structural integrity, and conformational exchange in proteins.

Key Features:

• Variable-temperature isotropic shift analysis: Operates on isotropic chemical shifts measured by solution NMR spectroscopy to probe local magnetic environment and hydrogen bonding.
• Automated tracking algorithm: Extends initial single-temperature ^1H–^15N cross peak assignments to spectra acquired over a range of temperatures.
• Temperature-coefficient calculation: Computes amide proton and nitrogen temperature coefficients by fitting chemical shift versus temperature data to linear models.
• Nonlinearity detection (curvature): Detects systematic deviations from linearity in amide proton temperature dependences that indicate fast exchange between distinct conformational states.

Scientific Applications:

• Folded protein structural analysis: Characterizes temperature-dependent changes in amide proton and nitrogen chemical shifts to report on hydrogen bonding and structural integrity in folded proteins.
• Disordered protein analysis: Evaluates temperature effects on chemical shifts in intrinsically disordered proteins to assess local structuring and dynamics.
• Mutational and ligand impact assessment: Assesses the effects of mutations, binding events, and solution conditions on local magnetic environments and protein energetics.
• Thermodynamic correlation: Enables correlation of local chemical-shift–based observations with global thermodynamic parameters often measured by calorimetric methods.

Methodology:

Automated tracking of ^1H–^15N cross peak assignments across temperatures, linear fitting of chemical shift versus temperature to obtain temperature coefficients, and detection of curvature (systematic deviations from linearity) in amide proton temperature dependences.