PRELIMINARY-STUDY OF SUBSTRATE-BINDING TO THYMIDINE KINASE BY TRANSFERRED NOE

A series of substrates with different values of dissociation constants K-d characteristic of their interaction with thymidine kinase (TK) has been studied (thymidine, acyclovir and tricycle). In thymidine-TK solutions ho transferred NOEs were observed which was attributed to the fact that the dissociation constant K-d is too low (similar to 8 mu M). In both acyclovir and tricycle, however, K-d proved sufficiently high (similar to 400 mu M) to allow for the observation of negative (transferred) NOEs. Series of NOESY spectra were recorded for tricycle (positive NOEs) and for the tricycle-TK complex (negative NOEs). The NOE pattern remains the same in both cases which indicates that the structure of the ligand does not change significantly upon binding to TK. The analysis of correlation patterns proves that the orientation of the aliphatic chain of tricycle with respect to the aromatic rings is characteristic of the syn conformation.