[Low-molecular cytolysins and trypsin inhibitors from sea anemone Radianthus macrodactylus. Isolation and partial characterization]. / Nizkomolekuliarnye tsitoliziny i ingibitory tripsina iz morskoi aktinii Radianthus macrodactylus. Vydelenie i chastichnaia kharakteristika.

Two low-molecular cytolytic toxins (RmI and RmII) and four trypsin inhibitors were isolated from the aqueous extract of sea anemone Radianthus macrodactylus. The method of isolation involved precipitation with acetone, gel filtration on acrylex P-4, ion-exchange chromatography on CM-32 cellulose, affinity chromatography on trypsin-binding sepharose 4B, ion exchange chromatography on an Ultrapore TSK CM-3SW column, and reversed phase HPLC on a Silasorb C18 column. RmI, RmII, and JnI inhibitor displayed molecular masses 5100, 6100, and 7100 Da, respectively, when subjected to SDS-PAGE. The isoelectric points were 9.2 and 9.3 for RmI and RmII, respectively. The amino acid composition and N-terminal amino acid residue (glycine) were determined for RmI, RmII, and JnI. Both proteins were nontoxic to mice and crabs. Hemolytic activity was determined to be 25 and 20 HU/mg for RmI and RmII, respectively, and their action on erythrocyte membrane was not inhibited by exogenous sphingomyelin. RmI and RmII exhibited antihistamine activity.

[The effect of chemical modification on the immunochemical activity of Rm-III neurotoxin from the anemone Radiantus macrodactylus]. / Vliianie khimicheskoi modifikatsii na immunokhimicheskuiu aktivnost' neirotoksina Rm-III iz aktinii Radiantus macrodactylus.

A chemical modification was used for studying the organization of antigenic determinants of neurotoxin Rm-III from the sea anemone Radianthus macrodactylus. Immunochemical experiments were performed using competitive enzyme-linked immunosorbent assay (ELISA) with polyclonal antibodies to Rm-III. The modification affected N-terminal amino group of Gly1, Lys4, Arg13, Trp30 residues, a residue in the Lys46-Lys47-Lys48 sequence, two different residues in the Asp6-Asp7-Glu8 sequence in two samples of the toxin, and two disulphide bonds. Only the modification of the disulphide bonds led to a considerable change in the toxin's affinity to antibodies. The modification of Trp30 resulted in two-fold decrease of the toxin concentration necessary for 50% inhibition of the test-system, whereas upon modification of any other amino acid residue this concentration increased but not more than by 2.2 times. It is suggested that Rm-III sequence lacks individual residues which are of great importance for the toxin's antigenic activity, its conformation being of vital importance for the formation of the toxin's antigenic determinants.

[Immunochemical study of neurotoxins from Radianthus macrodactylus actinin]. / Immunokhimicheskoe izuchenie neirotoksinov iz aktinin Radianthus macrolus.

Polyclonal antibodies to neurotoxin Rm-III from sea anemone Radianthus macrodactylus have been obtained. Constants of inhibition of the Rm-III binding to its antibodies by the homologous toxins have been determined. Antigenic activity of the second type toxins is shown to depend not only on the degree of homology but also no the type of substitution in the amino acid sequence. As shown by the calculation methods, the antigenic determinants of all the homologues have similar positions. Amino acid residues at positions 2, 11, 20, 28, and 46-48 seem to be included into the antigenic sites of the toxins studied.