Thesis Title: Subtitle - NMR Spectroscopy Research Group

18 Chapter 1. Introduction.
(Bugayevskiy et al., 1995) as shown in Figure 1.13. A Sanson-Flamsteed plot is a projection of a
sphere on a plane, and is commonly used in geography to project the globe on a map. The axes of
the Δχ-tensor penetrate the surface of a unitary sphere, and the penetration points can be identified
on the projection. This representation is convenient to highlight how reliable the fit of a Δχ-tensor
is in the context of the data and structure used for the calculation. For example, the Δχ-tensor found
for the ε subunit of DNA polymerase III is particularly well defined (Figure 1.14.a), while the
Sanson-Flamsteed plot corresponding to the fit for the θ subunit (in complex with ε) reveals more
uncertainties (Figure 1.14.b). Those differences are mainly due to the large distance (>15 Å) that
separates θ from the lanthanide bound to ε.
When docking a small molecule compound such as a drug to a protein, it is likely that the
Sanson-Flamsteed plot highlights large uncertainties because only a small number of PCSs can be
measured. To improve the situation, an important and desired feature would be to use the
information of the protein’s Δχ-tensor in order to improve the fit of the drug’s Δχ-tensor. The
resulting enhancements are illustrated in Figure 1.14.c (compared to Figure 1.14.b) for the ε/θ
protein-protein complex and are expected to be similar for small ligand-protein complexes.
In order to address the presented issues, it is required to have an efficient software package
to work with the Δχ-tensor. Chapter 3 presents the software package ―Numbat‖ (Figure 1.15) that
tries to meet all those needs.