High-resolution nuclear magnetic resonance spectra of selectively deuterated staphylococcal nuclease.

An analog of staphylococcal nuclease has been prepared in which all amino acids, except the six following, are fully deuterated: tryptophan; methionine; tyrosine, in ring positions 2 and 6; histidine, in ring position 2; aspartic acid and asparagine, beta-methylene; and glutamic acid and glutamine, gamma-methylene. The analog has a much simpler high-resolution nuclear magnetic resonance spectrum than the fully protonated enzyme. The effects of calcium ion and of the inhibitor 3', 5'-thymidine diphosphate on the spectrum of the analog were readily detected.