Search PubMed⌕ Search

Biomedical subjects

V L Boroviagin

Publications and source records attributed to V L Boroviagin.

At least 19 recordsLinked to original sources
PubMed1983

[The effect of phospholipid metabolites on the structure of model membranes].

The influence of 1,2-diacylglycerols on the structure of model membranes made of phosphatidylcholine or phosphatidylcholine-phosphatidylethanolamine and phosphatidylcholine-phosphatidylinositol mixtures was studied by 31P NMR and freeze-fracture technique. It was shown that 1,2-diacylglycerols (1,2-dipalmitoyl-rac-glycerol, 1-palmitoyl-2-oleoyl-rac-glycerol, 1,2-dioleoyl-rac-glycerol and also naturally occurring 1,2-diacyl-sn-glycerols) induced in the lipid bilayer markedly curved regions with concomitant formation of the folds and intramembrane particles. This process is accompanied by the appearance of isotropic signals in the 31P NMR spectra.

Freeze Fracturing↗
PubMed1979

[Temperature-dependent changes in the profile of the sarcoplasmic reticulum membrane hydrophobic zones].

The dependence of the state of the hydrophobic zone of rabbit sarcoplasmic reticulum (SR) membranes on temperature of the membrane fragment suspension before rapid freezing was studied by the freeze fracturing technique. It was shown that within the temperature range of--15-- +37 degrees C the amount of intramembrane particles and their distribution in the membrane plane and between their convex and concave surfaces do not practically depend on the temperature of the SR membrane suspension. This is indicative of the lack of correlation between the physical state of the phospholipid matrix (gel -- liquid crystal) before freezing and the nature of the profile of the membrane hydrophobic zone revealed after fracturing. The disturbances in the protein -- lipid interactions in the membrane under the effects of mersalyl or aqueous solutions of diethyl ester followed by complete inactivation of Ca2+-dependent ATPase lead to a decrease in the amount of intramembrane particles, which is especially well-pronounced at 37 degrees and -15 degrees C.

Animals↗
PubMed1976

[Biochemical and ultrastructural characteristics of the membranes of Streptococcus faecalis].

It is demonstrated by thin-section that S. faecalis cells (Strain BKM-B6) have no inner membranes, and their plasma membranes do not show any invagination into the cytoplasm. It is established that B and A fracture faces of the membranes in the intact bacteria, protoplasts, osmotic shock and sonicated membrane fractions contain uniformly distributed particles with a density of 200--400 and 4000--5000 particles/mu m2, respectively. Washing of the osmotic shock membrane fraction with a buffer solution of 0.25 M tris-SO4 with 2 M LiCl removes 35--40% of non-membrane proteins. Further washing (repeated 3 times) of the fraction with 0.001 M tris-SO4 removes additionally 40% of the protein, decreases the ATPase activity by 80%, and slightly decreases the cross-section of the membranes, but it does not affect of their A and B fracture faces. The membrane fracture faces A in all fractions exhibit small areas with tetragonally packed particles (with a tetragon size of 150 A X 150 A and a density of 20000--22000 particles/mu m2). These areas seem to be responsible for changing in the isolated membrane properties. Treatment of the washed membrane fractions with 0.2% triton X-100 results in a decrease of the vesicle sizes and appearance of drastic changes of their fracture faces. Changes of the membrane fracture faces under the action of triton X-100 are likely to be due to a breakdown in the hydrophobic interaction between the protein and lipid components. As it is shown by freez-fracturing technique, osmotic shock and sonicated membrane fractions contain 95% and 50% of rightside-out vesicles. It correlates with biochemical data on the membrane orientation of vesicles in different fractions.

Cell Membrane↗
PubMed1976

[Comparative study of membranes of Streptococcus faecalis and Micrococcus lysodeikticus].

A comparative study of ultrastructure and IR-spectroscopy of osmotic shock membranes from cells of glycolyzing (Streptococcus faecalis) and respiring (Micrococcus lysodeikticus) bacteria, was made. The S. faecalis and M. lysodeikticus membranes differ in their cross-section. Treatment of the preliminary washed membranes of S. faecalis and M. lysodeikticus with a low ionic strength solution removes 40% and 70% of their proteins respectively, decreases the membrane cross-section but does not change their fracture faces. Pre-cooling of the membrane suspensions within the temperature range of +5 degrees-10 degrees results in the appearance of large smooth areas on S. faecalis membrane fracture faces, but does not affect the ones of M. lysodeikticus membrane. Treatment of the washed suspensions with Triton X-100 results in the appearance of drastic changes of S. faecalis membrane fracture faces and does not change the fracture faces of M. lysodeikticus membranes; treatment by the detergent does not alter the IR-spectroscopy of membranes of both bacteria. Treatment of S. faecalis and M. lysodeikticus membranes with high temperature irreversibly changes the structure of 20% and 40% of protein components respectively,, but does not affect the distribution of the subparticles on their fracture faces. It is assumed that the differences found are determined by the composition of lipid components of the membranes studied and that the amount of proteins closely bound with lipids in the membranes of S. faecalis is likely to be greater than that of M. lysodeikticus membranes.

Bacterial Proteins↗
PubMedDate not supplied

[IR-spectroscopic study of cytochrome C-phospholipid lipoprotein and proteolipid model membranes].

It is shown by the methods of IR-spectroscopy and peptide hydrogen-deuterium exchange that a) considerable changes in the protein spectra occur (beta-conformation in the protein structure appears) during the interaction in water of cytochrome c molecules with lipid membranes containing negatively charged polar groups; b) further significant changes of the protein spectrum occur under the action of 1% OsO4 and heating up to n plus 95 degrees C; c) the conformational state of the pure protein in water; after the treatments of the proteolipid memebranes with 1% OsO4 and heating up to n degrees C no significant changes of protein spectrum occur, that may suggest hydrophobic interactions between the protein and lipids; d) the treatment of both pure cytichrome c and the model membranes with 1% glutaraldehyde, 30, 60% ethanol and acetone solutions in water does not reveal substantial changes in IR-spectra of the protein moiety.

Cytochrome c Group↗