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Y Kanemasa

Publications and source records attributed to Y Kanemasa.

At least 37 records · Page 2Linked to original sources
PubMed1985

The effect of head group structure on phase transition of phospholipid membranes as determined by differential scanning calorimetry.

The phase transition characteristics of cardiolipin and phosphatidylglycerol suspensions were investigated by differential scanning calorimetry. The phase transition temperatures for dimyristoylphosphatidylglycerol, tetramyristoylcardiolipin, dipalmitoylphosphatidylglycerol and tetrapalmitoylcardiolipin were 25.0, 47.0, 40.5 and 62.2 degrees C, respectively. The phase transition temperature for a mixture of two analogous phospholipids was higher than that for phosphatidylglycerol alone, but lower than that for cardiolipin alone. It increased along with cardiolipin content. The phase transition temperature for cardiolipin was increased in the presence of divalent cations, particularly Ca2+. The results indicate that the head group of cardiolipin by itself can increase the phase transition temperature.

Calorimetry, Differential Scanning↗
PubMed1985

Characterization of a glycophospholipid of Streptococcus pyogenes-derived L-form.

A glycophospholipid was detected as a major lipid in the L-form derived from Streptococcus pyogenes. The glycophospholipid was purified and chemically analyzed. From its phosphorus:glucose:glycerol molar ratio of 1:2:2 and mass spectrum, the deacylated glycophospholipid was identified as glycerophosphoryldiglucosylglycerol. This structural assignment was confirmed by thin layer chromatography of the lipid itself, which comigrated with known phosphatidyldiglucosyldiglyceride from S. faecalis. A possible mechanism for biosynthesis of the glycophospholipid in the L-form that invokes known biosynthetic processes involved in glycophospholipid metabolism in related bacteria is proposed.

Chromatography, Paper↗
PubMed1984

Determination of surface charge of some bacteria by colloid titration.

The surface charge of bacteria is always negative except below pH 2. The negative charge depends mainly upon phosphate and carboxyl groups. The charge of six kinds of bacteria was determined by colloid titration between pH 2 and 11. When there is amino group on the cell surface, it is positive as ammonium cation between pH 2 and 10, and it combines with the negative groups to neutralize the negative charge. In the presence of formalin, the colloid titration results show that the free amine is blocked by formalin, and the amino group can be estimated by the difference between the two titration results. Above pH 10, the titration results of Escherichia coli and Salmonella typhi in the presence of formalin implied the existence of guanidyl group. The titration results of living bacterial suspensions were quite the same as those of heat-killed ones.

Amines↗
PubMed1982

Detection of functional group on the liposome surface by colloid titration.

Suspensions of phospholipid liposomes (phosphatidylcholine, phosphatidylglycerol, phosphatidylethanoline and phosphatidylserine) were examined by colloid titration with polydiallyldimethylammonium chloride and potassium polyvinylsulfate as polycationic and polycationic and polyanionic titrants, respectively. In addition, the electrophoretic mobilities of the liposomes were measured with a cytopherometer. The following conclusions are drawn from the results of the titration: Phosphate and ammonium groups of phosphatidylcholine in liposomes form intramolecular or intermolecular salt linkages. Phosphate on the surface of phosphatidylglycerol liposomes shows a constant dissociation at above pH 3. Liposomes of phosphatidylethanolamine have no charge at low pH and a maximum negative charge above pH 10.5. On the surface of phosphatidylserine liposomes, the carboxyl group is completely dissociated at pH 6-7 and the phosphate group is released completely by the conversion of the ammonium ion to an amino group above pH 10.5. Stemming from these results, colloid titration can reveal the dissociation or the situation on the surface of liposomes more precisely than electrophoresis. Thus colloid titration is useful for determining the states of functional groups on the surface of phospholipid liposomes.

Colloids↗
PubMed1980

Alteration in phospholipid composition of Staphylococcus aureus during formation of autoplast.

The phospholipid composition of autoplasts (protoplasts made by autolysis of Staphylococcus aureus 209P was examined. The autoplasts were prepared by incubation of 209P cells in 1.2 M sucrose--0.33 M acetate buffer (pH 5.8). Cardiolipin comprised nearly half the total phospholipid in these autoplasts. Autoplasts had a lower phosphatidylglycerol content than intact cells but similar lysylphosphatidylglycerol content. The increase in cardiolipin content during release of autoplasts was not affected by pH or temperature. The result indicates that removal of the cell wall caused the increase in cardiolipin content. The total amount of phospholipids increased slightly during autoplast formation, but there was no significant increase in fatty acids or diglycerides. The changes of phospholipid composition during formation of the autoplast was due to de novo synthesis of cardiolipin from phosphatidylglycerol.

Bacteriolysis↗
PubMed1979

Lipid composition of Staphylococcus aureus and its derived L-forms.

Two strains of Staphylococcus aureus (Newman and Tazaki) and their derived L-forms were cultured in serum-containing broth and the differences in their lipid compositions were analyzed. Cardiolipin accounted for more than 50% of the total phospholipid phosphorus in L-forms, but for less than 25% in parent bacteria. The cardiolipin content of L-forms was very high through all growth phases, although it increased gradually as growth proceeded. Significant amounts of cholesterol and its esters were present in parent strains and L-forms, all of which incorporated serum cholesterol into the cell membrane. On the other hand, they could be detected in the L-forms but not in the parent strains when they were cultured in serum-free broth. To examine the ability of L-forms to synthesize cholesterol, the cholesterol content of L-forms cultured in serum-free broth was compared with that of the medium. The results indicated that staphylococcal L-forms could synthesize cholesterol and its esters. These differences in lipid composition suggested that modification of membrane lipids may occur as an adaptational change in response to the disappearance of the cell wall.

Cardiolipins↗
PubMed1979

Presence and synthesis of cholesterol in stable staphylococcal L-forms.

The sterol which was present in two strains of a stable staphylococcal L-form was analyzed by gas-liquid chromatography and combined gas-liquid chromatography-mass spectrometry. The retention time of the sterol on gas-liquid chromatography was the same as that of authentic cholesterol. Analysis of the sterol by mass spectrometry showed a molecular ion at an m/e of 386 and the same patterns of major ions above an m/e of 145 as those of authentic cholesterol. As a result, the sterol in staphylococcal L-form was identified as cholesterol. A parent strain and its L-forms were cultured in medium containing [14C]acetate, and the synthesis of cholesterol was examined. In the L-forms, 0.52% of the total lipid radioactivity was found in cholesterol fraction, whereas no significant radioactivity was detected in the cholesterol fraction of the parent strain, indicating that staphylococcal L-forms have acquired the capacity to synthesize cholesterol.

Cholesterol↗
PubMed1979

Effect of glucose and oxygen on the structure of the plasma membrane of Staphylococcus aureus.

The effects of glucose and oxygen on the formation of the plasma membrane of Staphylococcus aureus were studied. Phospholipids were consistent components of the membrane and were not affected by glucose or oxygen. Phospholipid fatty acids in cells grown in glucose containing media were rich in Ceven (C18, C20) fatty acid chains, whereas cells grown in glucose deficient media (normal broth) had anteiso Codd (C15,C17) fatty acid chains in place of Ceven chains. This may indicate increased membrane rigidity of the cells grown in glucose containing media. Cytochromes and ATPase were present in the membrane from cells grown in normal broth, but were deficient in the cells grown in glucose containing media. Polypeptide analysis of the membrane proteins showed a deficiency of the bands corresponding to these enzymes. They were not induced by the additionof oxygen to cells grown in glucose containing media. It was concluded that glucose was the dominant factor inhibiting the formation of these membrane enzymes.

Cell Membrane↗
PubMed1978

Adaptational change in proline and water content of Staphylococcus aureus after alteration of environmental salt concentration.

Adaptation of Staphylococcus aureus to a change in salinity was studied by estimating the intracellular content of water and proline after alteration of the salt concentration of the culture medium. The intracellular water content of S. aureus cultured in normal broth was 1.70 g/g (dry weight). After transfer to 1.8 M NaCl-containing broth, the water content decreased to 0.80 g/g (dry weight) within 1 min. After changing the salt concentration of the medium, intracellular free proline (assumed to be one of the osmoregulators in S. aureus) increased gradually from 0 to 1,400 mumol/g (dry weight) during 30 min of incubation at 37 degrees C. The water content rose to 0.88 g/g (dry weight) in 30 min. Proline was not taken up at 0 to 4 degrees C, suggesting that the process was one of active transport. The salt tolerance of S. aureus, therefore, appears to occur initially by dehydration of the cell after transfer from a medium of low salinity to one of high salinity and then by accumulation of proline, which carries water into the cell with it.

Adaptation, Physiological↗
PubMed1976

The salt-resistance mechanism of Staphylococcus aureus examined by salt-sensitive mutants.

Two NaCl-sensitive mutants of S. aureus 209P (S-16 and S-23) were isolated after treatment of the parental strain with N-methyl-N'-nitro-N-nitrosoguanidine. Examination of the lipid components revealed that S-16 contained no cardiolipin and that S-23 contained only a small amount of cardiolipin. An increase of cardiolipin was indispensable for S. aureus proliferation in high NaCl medium.

Cardiolipins↗
PubMed1976

Characterization of the glycolysis pathway and the plasma membrane of Lactobacillus and Bifidobacterium strains.

The characteristics of the glycolytic pathway and the plasma membrane of Lactobacillus and Bifidobacterium were studied. The enzyme system of glycolysis (hexokinase, glucokinase and pyruvate kinase) which is the main source of energy in the anaerobic condition was localized in the cell soluble fraction (cytoplasma) of all species examined. Neither electron transfer chain components nor oxidase activities were found in anaerobically cultured Lactobacillus and Bifidobacterium. Adenosine triphosphatase (ATPase) activities were mainly localized in the plasma membrane, suggesting that membrane ATPase is playing a key role in membrane transport and ATP synthesis of anaerobic bacilla. SDS-polyacrylamide gel electrophoresis of membranes showed remarkable differences between the polypeptides patterns of B. adolescentis and B. bifidum. Such peculiarities in polypeptide patterns among the same genus may be useful in the identification of species.

Adenosine Triphosphatases↗