Protein dynamics is at the heart of all cellular processes. Here, we utilize the dHis-Cu II NTA label to obtain site-specific information on dynamics for both an a-helix and b-sheet site of GB1, the immunoglobulin binding domain of protein G. Spectral features found in our CW-EPR measurements were consistent with the overall rigid nature of GB1 and with predictions from molecular dynamics simulations. Using this information, we show the potential of this approach to elucidate the role of dynamics in substrate binding of a functionally necessary a-helix in human glutathione transferase A1-1 (hGSTA1-1). We observe two dynamical modes for the helix. The addition of the inhibitor GS-Met and GS-Hex resulted in hGSTA1-1 to favor the more rigid active state conformation, while the faster mode potentially aids the search for substrates. Together the results illustrate the remarkable potential of the dHis-based labelling approach to measure sitespecific dynamics using room temperature lineshape analysis.

The structure of thymidylate kinase from Candida albicans, determined by X-ray crystallography, is reported to a resolution of 2.45 Å with a final R of 0.223. Thymidylate kinase from C. albicans possesses a unique 15-residue loop that is not seen in thymidylate kinases from other genera. The structure reported here reveals that the conformation of this loop is constrained by both intra- and intersubunit hydrogen bonding, and a number of key residues in this loop are conserved among different Candida species that are medically important. The substrate specificity of the enzyme was determined using a novel nuclear magnetic resonance-based assay as well as a traditional coupled assay. The enzyme is active against 3'-azido-3'-deoxythymidine monophosphate and moderately active with dGMP. The distinct functional and structural differences between the C. albicans enzyme and the human enzyme suggest that thymidylate kinase is an appropriate target for the development of new antifungal agents.

Specific 13C labeling of Thr methyl groups has been accomplished by growth of a standard laboratory strain of Escherichia coli on [2-13C] glycerol in the presence of deuterated isoketovalerate, Ile, and Ala. Diversion of label from the Thr biosynthetic pathway is suppressed by including Lys, Met, and Ile in the growth media. This method complements the repertoire of methyl-labeling schemes for NMR structural and dynamic studies on proteins and is particularly useful for the study of nucleic acid binding proteins due to the high propensity of Thr residues at protein-DNA and -RNA interfaces.

Protein dynamics is at the heart of all cellular processes. Here, we utilize the dHis-Cu II NTA label to obtain site-specific information on dynamics for both an a-helix and b-sheet site of GB1, the immunoglobulin binding domain of protein G. Spectral features found in our CW-EPR measurements were consistent with the overall rigid nature of GB1 and with predictions from molecular dynamics simulations. Using this information, we show the potential of this approach to elucidate the role of dynamics in substrate binding of a functionally necessary a-helix in human glutathione transferase A1-1 (hGSTA1-1). We observe two dynamical modes for the helix. The addition of the inhibitor GS-Met and GS-Hex resulted in hGSTA1-1 to favor the more rigid active state conformation, while the faster mode potentially aids the search for substrates. Together the results illustrate the remarkable potential of the dHis-based labelling approach to measure sitespecific dynamics using room temperature lineshape analysis.

The HMCM[CG]CBCA experiment (J. Am. Chem. Soc. (2003), 125, 13868–13878) correlates methyl carbon and proton shifts to Cγ, Cβ, and Cα resonances for the purpose of resonance assignments. The relative sensitivity of the HMCM[CG]CBCA sequence experiment is compared to a divide-and-conquer approach to assess whether it is best to collect all of the methyl correlations at once, or to perform separate experiments for each correlation. A straightforward analysis shows that the divide-and-conquer approach is intrinsically more sensitive, and should always be used to obtain methy-Cγ, Cβ, and Cα correlations. The improvement in signal-to-noise associated with separate experiments is illustrated by the detection of methyl-aliphatic correlations in a 65 kDa protein-DNA complex.