We propose to continue our investigations of the electronic and geometric properties of the likely reactants, intermediates, and products of biotinmediated carboxylations, decarboxylations, and transcarboxylations, and at the same time inaugurate our studies of model participants in the biotinavidin interaction. Biotin is a vitamin responsible for the uptake and transfer of carbon dioxide; the enzymes it serves are involved in key metabolic processes such as gluconeogenesis, fatty acid synthesis and propionate elaboration. The biotin enzymes share a number of architectural and mechanistic characeristis; our results will be germane in the understanding of them all. Avidin is a protein found in the whites of most poultry eggs; it binds biotin with a tenacity unparalleled in non-covalent interactions. The biotin-avidin interaction is becoming an extremely important tool in both separation and purification science and in cytochemical and immunological localization procedures. From a mechanistic point of view the biotin-avidin interaction is only poorly understood. In our studies of biotin as coezyme and as a biochemical tool we will investigate, by the techniques of experimental high resolution x-ray diffraction and theoretical ab initio quantum mechanics, the properties of model systems germane to these functions. Both techniques yield detailed information about the geometric and electronic properties of molecules. by looking at individual participants in biotin-mediated processes we can surmise the states of key intermediates prior to interaction. By looking at pairs of participants, either by cocrystallization, by modeling electrostatic interaction from the experimentally determined properties of the individuals involved, or by computation of ensemble properties theoretically, we can surmise the dynamic processes involved in these functions of biotin. At the heart of these studies is a clearer understanding of the mechanisms, and in particular the electronic and geometric details, by which biotin acts.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
Project #
Application #
Study Section
Biophysics and Biophysical Chemistry A Study Section (BBCA)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Hauptman-Woodward Medical Research Institute
United States
Zip Code
Blessing, R H (1995) An empirical correction for absorption anisotropy. Acta Crystallogr A 51 ( Pt 1):33-8
Moss, G R; Souhassou, M; Blessing, R H et al. (1995) Computational studies of crystalline H3PO4. Acta Crystallogr B 51 ( Pt 5):650-60
Souhassou, M; Espinosa, E; Lecomte, C et al. (1995) Experimental electron density in crystalline H3PO4. Acta Crystallogr B 51 ( Pt 5):661-8
Blessing, R H (1995) On the differences between X-ray and neutron thermal vibration parameters. Acta Crystallogr B 51 ( Pt 5):816-23
DeTitta, G T; Weeks, C M; Thuman, P et al. (1994) Structure solution by minimal-function phase refinement and Fourier filtering. I. Theoretical basis. Acta Crystallogr A 50 ( Pt 2):203-10
Weeks, C M; DeTitta, G T; Hauptman, H A et al. (1994) Structure solution by minimal-function phase refinement and Fourier filtering. II. Implementation and applications. Acta Crystallogr A 50 ( Pt 2):210-20
Miller, R; DeTitta, G T; Jones, R et al. (1993) On the application of the minimal principle to solve unknown structures. Science 259:1430-3
Langs, D A; Blessing, R H; Duax, W L (1992) Crystal structure of valinomycin-monohydrate cage complexes crystallized from dioxane. Int J Pept Protein Res 39:291-9
Souhassou, M; Lecomte, C; Blessing, R H et al. (1991) Electron distributions in peptides and related molecules. 1. An experimental and theoretical study of N-acetyl-L-tryptophan methylamide. Acta Crystallogr B 47 ( Pt 2):253-66
Guo, D Y; Blessing, R H; Hauptman, H A (1991) On integrating the techniques of direct methods with anomalous dispersion. II. Statistical properties of the two-phase structure invariants. Acta Crystallogr A 47 ( Pt 4):340-5

Showing the most recent 10 out of 11 publications