Slight changes of the conformation in the positions of the amino acids building up the hydrophobic pocket which forms the binding site for the pyrimidine ring compensate for the additional methyl group at the 6’ position. In the observed conformation of the GMThDP, the 6’methyl group comes close to the 4’ methyl group of the thiazolium ring. The side chain of Glu418 and residue 118 shift their position slightly to avoid too close contact with the pyridin ring of the NlThDP and N3ThDP analogs, respectively.