THE INFLUENCE OF DELETION OF 9 RESIDUES AT THE C-TERMINAL OF STAPHYLOCOCCAL NUCLEASE ON THE CONFORMATION OF THE ENZYME

Combining the multidimensional NMR with CD and fluorescence methods, the solution conformations of staphylococcal nuclease from V8 strain (SNase) and its N-terminal 1-140 fragment (SNasel40) as well as the ternary complex of SNasel40, TMP (Thymidine 5'-monophosphate), and Ca2+ have been studied. The experimental data reveals that deletion of the nine residues at the C-terminal of SNase has influenced the enzyme conformation and activity. Inspection of 3D structure of staphylococcal nuclease indicates that the hydrogen bonds formed between a and (3 subdomains of the enzyme must be disturbed by the deletion of the amino acid residues succeeding Trpl40 of SNase. In consequence, the changes in the interaction between amino acid residues located away from enzyme active site will disturb the confonnational state of enzyme active site, and thus influence on the activity of enzyme protein.