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Several computational studies are conducted to analyze the different properties exhibited during the hydrogen bonding taking place in the active site of ketosterois isomerase. The changes taking place in the NMR chemical shifts and electronic absorption spectra of the system due to the bonding are also discussed.

A method to identify and correct the departures from the Stark model due to direct hydrogen bonding based on comparison of [super 13]C NMR chemical shifts and IR frequencies each calibrated in turn by a solvatochromic model is presented. The experimental observations could be applied to a thiocyanate-modified protein, ketosteroid isomerase to demonstrate that the changes in electrostatic field could be measured within the complex protein environment even in the background of direct hydrogen bonding to the probe.

NMR spectroscopy is used to determine the solution structure of oxidized ERp18, the smallest member of the protein disulfide isomerase (PDI) family of proteins to contain a Cys-Xxx-Xxx-Cys active site motif. The results confirmed a putative role for ERp18 within the cell as an oxidase, introducing disulfide bonds to substrate proteins, and also provide structural confirmation for role of ERp18 as a thiol-disulfide oxidoreductase.

DNA cleavage assays, saturation transfer difference [super 1]H NMR spectroscopy, and enzyme-drug binding studies were conducted to define interactions between etoposide and human topoisomerase II[alpha]. The results suggest that the binding of etoposide to human topoisomerase II[alpha] is driven by interactions with the A- and B-rings and potentially by stacking interactions with the E-ring.