[The nature of glycogen complexing with iodine in the presence of CaCl2]. / Priroda kompleksoobrazovaniia glikogena s iodom v prisutstvii CaCl2.

The absorption and dichroism of muscle glycogen--iodine complexes depending on CaCl2 concentration were studied. It was shown that besides intensification of glycogen staining with iodine, high concentrations of CaCl2 cause destabilization of the alpha-glucan helix as well as disturbances in the formation of a specific chromophore of the iodine-glycogen complex which manifest themselves as a loss of dichroism. The stained chromophore formed by a simultaneous decrease in the dichroic absorption seems to be generated in the non-helical regions of the glycogen molecule and is thus nonspecific. This nonspecific chromophore is a potential source of errors in spetrophotometrical assays of glycogen structure. Study of rabbit skeletal muscle and liver glycogens by the Krisman method based on the use of concentrated solutions of CaCl2 failed to reveal any differences in glycogen structure that are normally detectable at low concentrations of CaCl2. The unfavourable effect of high concentrations of CaCl2 on helix formation should be taken into consideration when studying the stoichiometry of iodine interaction with alpha-glucan.

[Effects of neutral salts on the conformational state of glycogen, interacting with iodine]. / Vliianie neitral'nykh solei na konformatsionnoe sostoianie glikogena, vzaimodeistvuiushchego s iodom.

The effects of salts on helix formation of linear (outer) chains of branched alpha-glucane, muscle glycogen, was judged upon by the state of polyiodine chromophore of the iodine reaction surrounded by a polysaccharide asymmetric helix and recorded by the circular dichroism method. It was demonstrated that apart from the known changes in the absorption of the iodine-glycogen complex the salts induce changes in the ellipticity by affecting the helix formation of the linear chains of the polysaccharide. The nature of these effects depends on the type and concentration of the salt used. Monovalent metal salts produce a more favourable effect on helix formation than the divalent metal salts. Among divalent metal salts transient metal salts produce a weaker effect. The action of neutral salts on helix formation is of dual nature: helix formation and helix destruction. The helix formation is largely impaired by high concentrations of LiCl (greater than 6 M) or CaCl2 (greater than 2M). It was shown that a certain role in the mechanism of neutral salt action on helix formation belongs both to electrostatic and lyotropic effects. The latter determine the effects of salts on helix formation at concentrations above the monomolar one, when the specific effect of a salt is especially well-pronounced. The salts which enhance the orderliness of H2O structure produce a favourable effect on helix formation of the linear polysaccharide chains and, consequently, on the iodine reaction. In terms of molar efficiency of their action on the iodine reaction the salts correspond to the Hofmeister lyotropic sequence.

[Effect of fructose derivatives on platelet aggregation]. / Vliianie proizvodnykh fruktozy na agregatsionnuiu sposobnost' trombotsitov.

Fructose diphosphate, fructose monophosphate and inorganic phosphate decrease platelet aggregation. Fructose does not affect the function under study. The most pronounced antiaggregation action is displayed by fructose diphosphate which enhances calcium binding with thrombocytic membranes. The action of fructose diphosphate depends on the time of its presence in the blood channel. Fifteen minutes after injection the substance inhibits the formation of experimental thrombocytic thromboses. After one hour such an effect does not manifest since fructose diphosphate is absent from the blood flow by that time.