CHROMIUM COMPLEXES OF INSULIN AND RELATED COMPOUNDS.
Annual progress rept.,
MARYLAND UNIV COLLEGE PARK DEPT OF CHEMISTRY
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In performing its biological role of enhancing the action of insulin, CrIII presumably is in the form of some specific compound formed by a sequence of reactions with various ligands of the biological system. The relative tendencies of such ligands to coordinate with CrIII can be determined by sequential dialysis, which measures their relative abilities to complete with OH- ion and other substances that can convert CrIII to non-diffusible polymeric compounds. Dialysis curves of reaction mixtures at physiological pH are obtained at intervals. As the reaction mixture ages the change in area under the curve dialysis equilibrium attained vs. time is a sensitive indicator of occurrence of reactions resulting in increased molecular size and consequent decrease in rate of diffusion of the CrIII compounds. It has previously been shown that pyrophosphate, triphosphate and citrate are exceptionally effective. Most of the compounds of the Krebs cycle, several compounds of the glycolytic chain, and various other biological compounds have now been evaluated. The results of many experiments point to the very significant conclusion that the most effective biological compounds are the phosphate esters these apparently are far more likely to coordinate with CrIII than other biological coordinating and chelating agents such as the amino acids, for example. Thiamine pyrophosphate, ATP and ADP are about as effective as inorganic pyrophosphate and triphosphate. Fructose-1,6-diphosphate and 3-phosphoglycerate are also exceptionally effective except for these two, which can chelate, the derivatives of monophosphoric acid tested were ineffective. Author