title: Change in effective pH of salt solutions on freezing, as evidenced by altered reactivities of heme alpha towards carbonyl reagents.
abstract: Addition of NaHSO3 or HCN to the formyl group of heme alpha was greatly accelerated by freezing reaction mixtures prepared in aq. Na2CO3, and freezing resulted in characteristic color and spectral changes of the solutions. Similar changes were observed on decreasing the pH of alkaline reaction mixtures with HCl at room temperature, indicating that the effective pH of certain salt solutions is greatly lowered by freezing. The reactivity of the formyl group changed depending on the redox state of the heme iron and the species of ligand.
mesh_terms: D002254:Carbonates; D003486:Cyanides; D005615:Freezing; D006418:Heme; D006851:Hydrochloric Acid; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles; D012964:Sodium; D012965:Sodium Chloride; D013447:Sulfites
chemical_list: D002254:Carbonates; D003486:Cyanides; D007093:Imidazoles; D013447:Sulfites; D006418:Heme; D012965:Sodium Chloride; D012964:Sodium; D006851:Hydrochloric Acid