Myra N. Williams

Proton magnetic resonance studies of human hemoglobin: Histidine titrations

Abstract The 100-MHz proton magnetic resonance (PMR) spectra of human hemoglobin in the oxy, deoxy, and met forms are reported from 680 to 930 Hz downfield from external tetramethylsilane. In this region the spectra show 5 to 9 titrable, occasionally overlapping resonances that can be assigned to the C-2 protons of histidines. The peaks with a line width of approximately 10 Hz, shift upfield about 100 Hz upon deprotonation of the histidine rings. In oxy- and methemoglobin the observed histidines exhibit similar pK values. Deoxyhemoglobin, when compared to oxyhemoglobin, has several histidine residues which show changes in pK values.

Dihydrofolate reductase from a methotrexate-resistant Escherichia coli: proton magnetic resonance studies of complexes with folate and methotrexate.

Abstract Proton magnetic resonance studies of 1:1 complexes of E. coli dihydrofolate reductase with folate and methotrexate were performed. A resonance at 1850 Hz in 1:1 enzyme-folate was assigned as the C-7 proton of bound folate by comparison with the spectra of enzyme complexed with folate specifically deuterated at C-7. The first order rate constant for folate dissociation was calculated to be less than 110 sec −1 . Four of the five histidine residues exhibited the same pKs and chemical shifts in the two complexes with pK values of 8.0, 7.3, 6.5 and ∼5. However, one histidine increased its pK by 0.7 units (6.25→6.95) and its C-2 proton resonance shifted upfield 50 Hz when folate was substituted for methotrexate. Comparison of these results with those of chemical modification and ultraviolet difference spectroscopy experiments suggests that this histidine may be in the folate binding site — possibly near the pteridine portion of that site.

Future Directions in Integrated Information Systems: Is There a Strategic Advantage?

Major advances in hardware, software, and connectivity of devices during the past decade are making new approaches to information management feasible. Although current software and hardware can meet specific information needs, generalised integrated solutions are not yet available. A number of companies have had the capability of merging chemical and biological data for years. In addition, software is available that permits text and graphics to be merged in a single document. In fact, most specific information needs can be met today by building specialised bridges between existing databases. However, problems of redundancy, incompatible systems, paucity of standards, numerous user interfaces and closed architectures argue that better solutions must be found. An immediate option is to use a windowing approach that facilitates the movement of information from one system to another. While this provides excellent functionality to the computer expert, it does not meet the broad based needs of most scientific and management staff. The increasingly competitive environment of the pharmaceutical industry mandates that information be readily available for effective decision making at all levels within the corporation. In response to this need, future information systems will utilise a common interface and hence one set of commands for accessing numerous databases. Software will adopt an open architecture so that only one graphics editor, one text editor, etc., will be required. The system will be capable of handling numerous different data types including text, chemical structures, spectra, graphs, restriction maps, among others. Moreover, even when integrated in a report, the data types will maintain their integrity; hence, when the report is distributed electronically, the underlying data can stay associated with it. And, finally, future information systems will exist in a multivendor, distributed environment. The driving force for these changes is the need to improve the productivity of research. Moreover, the emphasis reflects the fact that information is now a crucial component of strategic management.

Research and the Pharmaceutical Environment

The pharmaceutical industry is often highlighted as one of the healthier industries in the United States, yet its environment has been turbulent and the challenges are enormous. Today I will discuss that environment from the point of view of research at the Merck Sharp and Dohme Research Laboratories (MSDRL) — specifically, what factors influence R & D within Merck, and what impact research has on manufacturing.