[The effect of proteolytic cleavage of potato virus X coat protein on its ability to self-assemble with RNA and viral infectivity]. / Vliianie proteoliticheskogo rasshchepleniia belka obolochki X-virusa kartofelia na ego sposobnost' k rekonstruktsii s RNK i na infektsionnost' virusa.

The process of proteolytic cleavage of potato virus X coat protein molecules inside the virions and in the dissociated state in the course of their purification and storage has been studied. In agreement with the previous reports, the intact form (Ps) of the coat protein in the viral particles was found to be gradually cleaved to three discrete lower molecular forms (Pi, Pf, Pu). During the storage of the dissociated coat protein preparations further cleavage was observed with formation of at least three additional lower molecular weight forms (Ppa, Ppb, Ppc). The location of proteolytic cleavage sites leading to formation of Ppa form was determined. The shortened forms Pi, Pf, Pu and Ppa (and possibly Ppc) were found to be incorporated into the viral particles in the course of reconstitution in vitro with the viral RNA. Infectivity of the virus containing only intact (Ps) form of the protein was found to be two to three folds higher than that of the virus containing only Pf form of the coat protein.

Coenzyme non-specific glutamate dehydrogenase from Chlorella pyrenoidosa 82T: electron microscopic studies.

The constitutive coenzyme non-specific glutamate dehydrogenase (GDH) from Chlorella pyrenoidosa 82T was purified to homogeneity by column immunoaffinity chromatography and examined by an electron microscope. The enzyme molecule was found to be a hexameric oligomer composed of monomers arranged in three 2-point group symmetry in two layers slightly twisted round the 3-fold axis. The molecule is 8 +/- 1 nm in diameter and 10 +/- 1 nm in height. The enzyme molecules appear both to dissociate into trimers and to associate along the 3-fold axis forming linear aggregates under certain conditions. A tentative model of the Chlorella GDH molecule is proposed, which is very similar to those described for bovine liver GDH and GDH from Clostridium symbiosum.

[Comparison of antigenic properties of the X-potato virus and its coat proteins. Effect of proteolytic cleavage on antigenic characteristics]. / Sravnenie antigennykh svoistv x-virusa kartofelia i ego belka obolochki. Vliianie proteoliticcheskogo rasshchepleniia na antigennye kharakteristiki.

Antigenic properties of intact potato virus X (PVX) particles and of PVX coat protein (CP) preparations were compared using different modifications of ELISA test. In the competitive ELISA test (reaction in solution) antibodies to intact virus react much stronger with PVX than with CP while antibodies to CP react much stronger with CP than with PVX. In the direct ELISA test (reaction on the solid support) the difference in reactions of antiCP antibodies with PVX and CP is eliminated while the one in reactions of antiPVX antibodies with these antigens remains. No difference was registered in reactivity of PVX absorbed directly on polystyrene or on immunoglobulin-coated wells (sandwich ELISA) to antiCP antibodies.

[Three-dimensional reconstruction of bacterial viruses from electron microscopy data. Bacteriophage structure]. / Trekhmernaia rekonstruktsiia bakterial'nykh virusov po dannym élektronnoi mikroskopii. Stroenie bakteriofagov.

The structure of bacteriophages from different groups is presented based on the data obtained by the three-dimensional reconstruction, optical diffraction and filtration and electron microscopy techniques. The study made possible to suggest the scheme for the mechanism of sheath molecules rearrangement at contraction of bacteriophage tail sheath, the model of bacteriophage FI-1 connector. The structural elements for difference and relation of various bacteriophages are demonstrated.

[Three-dimensional reconstruction of bacterial viruses from electron microscopy data. Subjects and methods of study]. / Trekhmernaia rekonstruktsiia bakterial'nykh virusov po dannym élektronnoi mikroskopii. Ob''ekty i metody issledovaniia.

The review summarizes the results of the study of the spatial structure of bacterial viruses (phages) whose tails seem to be the most primitive contracting biological mechanism. Data on the spatial molecular rearrangement are important for understanding the processes of biological mobility. The computer and laser techniques used in order to obtain information on the three-dimensional structure of the object under study by its two-dimensional electron-microphotography are presented in the first part of the review. The second deals with application of the above mentioned techniques for the study of various bacterial viruses.

Characterization of bean mild mosaic virus: particle morphology, composition and RNA cell-free translation.

Virions of bean mild mosaic virus (BMMV) are built of 180 subunits of a single protein species of MW 40 x 10(3) [coat protein CP], packed into a T = 3 surface lattice. The capsomers on the five-fold symmetry axes protrude 2-3 nm from the particle surface. The virions encapsidate genome-size [approximately 4,200 nucleotides (nt)] as well as some heterogeneous RNAs of subgenomic size approximately 1,000-2,000 nt. In cell-free systems from Krebs-2 ascites cell extracts and rabbit reticulocyte lysates, genome-size RNA directed the synthesis predominantly of two polypeptides of MW 27 x 10(3) and 79 x 10(3) while the third major BMMV-specific polypeptide (MW 40 x 10(3), putative CP) seemed to be encoded by a shorter messenger RNA. The 'cap' analogue, m7GDP, partially inhibited BMMV RNA in vitro translation, suggesting that at least part of the BMMV-specific RNAs are capped. Oligo (dT)-cellulose column chromatography data suggested that poly(A)-tracts are absent from the BMMV genome. The data obtained confirm the previous classification of BMMV within the carmovirus group.

Association of rabbit muscle glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase. The biochemical and electron-microscopic evidence.

Rabbit muscle glyceraldehyde-3-phosphate dehydrogenase covalently bound to Sepharose was shown to form a complex with soluble 3-phosphoglycerate kinase. The strength of the association appeared to depend upon the functional state of both enzymes. The holoform of the dehydrogenase exhibited a lower affinity for the kinase than the enzyme-3-phosphoglycerol.NADH complex. The substrate-free 3-phosphoglycerate kinase associated much stronger with the acylated dehydrogenase than the kinase in complex with 1,3-diphosphoglycerate. Electron-microscopic evidence for the association of the soluble acyl-glyceraldehyde-3-phosphate dehydrogenase.NADH complex and 3-phosphoglycerate kinase was also obtained.