Use of Perturbed Gamma-Gamma Directional Correlations in the Study of Anomalous Water Structure.

摘要

Perturbed gamma-gamma directional correlation is a branch of nuclear spectroscopy. When two gamma rays from a radioactive nucleus are emitted in a cascade their directional correlation can be perturbed by the interaction of the nucleus with extranuclear fields. Very small tracer concentrations (10-12M) are usually quite sufficient to probe the internal structure of the medium. By using Ba-133ions the structure of water associated with the globular protein carbonic anhydrase was investigated. Water at the protein interface is highly ordered resembling ice in its properties. A study by this technique of water droplets condensed in capillaries showed that the abnormally high viscosity of the sample is not the result of covalent bonding but rather originates from exceptionally strong hydrogen bonding. The internal fields and symmetry characteristics of the active region and active site carbonic anhydrase were also investigated by using Co-57tracer. A straight-forward method leading to direct interpretation could advance all areas of biological science including such applied fields as nutrition,food preservation and numerous branches of biomedical research.