Gelation Phenomena Induced by Alkali-alcohol Treatment of 7S and 11S Components in Soybean Globulins

Transparent gels containing about 2% protein were obtained by mixing alkaline dope solution of 7S or 11S soybean proteins with alcohol. The 7S component showed the ability to form a stronger gel than the 11S. This phenomenon depended on pH and alcohol concentration. In 66 % ethanol, the viscosity of the 7S and 11S reached maxima at pH 11.4 and 11.2, respectively. Above these pH levels where further unfolding and dissociation into subunits of the protein molecules occur, the viscosity decreased rather. The effectiveness of alcohol to increase viscosity increased in the order; n-butanol < tert-butanol < n-propanol < iso-propanol < ethanol < methanol. Alcohols having minor hydrophobicity were more effective for increasing viscosity, but ethylene glycol was ineffective. The addition of NaCl or 2-mercaptoethanol to ethanol-mixed alkaline dope solutions resulted in the remarkable increment of the viscosity, especially for the 7S.     

Dynamics of appearance and disappearance of the ripple structure in multilamellar liposomes of dipalmitoylphosphatidylcholine

The physical properties of the pretransition (P beta'----L beta') of dipalmitoylphosphatidylcholine liposomes were investigated using freeze-fracture electron microscopy. The kinetics of pretransition examined in the previous paper using TEMPO spin probe (Tsuchida, K., et al. (1985) Biochim. Biophys. Acta 812, 249-254) was extensively studied by observing the ripple structures in the freeze-fractured surfaces at different time intervals. When the temperature is decreased from 38 degrees C to 30 degrees C, the ripple structure disappears in the following steps. The intervals between ripples begin to expand with the decrease of ripple density upon the temperature shift, and this process continues for several tens minutes. Then, each ripple disappears gradually and changes into a completely smooth surface at 3 h after the temperature shift. The comparison of relaxation times between the previous ESR measurement and the present experiment suggests that the fast relaxation observed in the previous study corresponds to the expansion of the intervals between ripples. On the other hand, the ripple structure of regular intervals appears rapidly in some places and then spreads over the whole area of fractured surface when the temperature is increased from 23 degrees C to 35 degrees C. The results obtained in this work and the previous ESR work strongly suggest that the formation and disappearance of ripple structure is closely related to the relaxation processes near the pretransition temperature.     

Activation of mouse peritoneal macrophages by synthetic glyceroglycolipid liposomes

Summary Liposomes composed of chemically synthesized glyceroglycolipids, such as 1,2-dipalmityl-[-cellobiosyl-(1 3)]-glycerol (Cel-DAG), 1,2-dipalmityl-[-lactosyl-(1 3)]-glycerol, or 1,2-dipalmityl-[-maltosyl-(1 3)]-glycerol, were found to enhance protective immunity against transplantable tumor cells (sarcoma 180) in ICR mice. Peritoneal exudate cells prepared from mice treated in vivo with Cel-DAG showed cytostatic activity in vitro against the mouse leukemia cell line, EL-4. Adherent cells separated from this preparation showed similar activity. Peritoneal cells from polypeptone-injected mice acquired appreciable cytostatic activity when incubated in vitro in the presence of glyceroglycolipid liposomes. The adherent cell fraction alone showed rather weak cytostatic activity when pretreated with the glyceroglycolipids, and full activity was restored by supplementing with the nonadherent cell fraction. The ability of glycolipids to induce tumoricidal effects was affected by cholesterol content: with increasing cholesterol content, the activities decreased. Cholesterol-free glycolipid liposomes were taken more efficiently by macrophages than cholesterol-containing liposomes. Cholersterol modifies the surface property of glyceroglycolipid liposomes. Activation of macrophages is responsible for enhancement of protective immunity against tumor cells by injection of these glycolipids in vivo.This work was supported in part by Grants-in-Aid (Nos. 58010010, and 59870076) for Scientific Research from the Ministry of Education, Science and Culture of Japan     

Interleukin-1 inhibits the secretion of gastric acid in rats: possible involvement of prostaglandin

To examine the hypothesis that interleukin-1 may inhibit the secretion of gastric acid, the present study was carried out using pylorusligated rats. Based upon three lines of evidence, we report here that interleukin-1, both endogenously released and exogenously administered, suppresses gastric acid secretion and that the interleukin-1-induced inhibition of acid output is possibly mediated by prostaglandin. First, lipopolysaccharide, a potent stimulant of the release and production of endogenous interleukin-1, caused the suppression of gastric acid, and this response was dose-related. Second, the intraperitoneal injection of interleukin-1 resulted in a dose-related inhibition of gastric acid output. Third, the administration of indomethacin completely blocked the suppression of gastric acid secretion induced by interleukin-1. These results demonstrated for the first time that IL-1 might be involved in the regulation of gastric secretion.     

Electron microscopic observations on tracheal epithelia of mice infected with Bordetella bronchiseptica

To clarify the pathogenesis of Bordetella in vivo infection, the tracheal epithelia of mice were examined in detail by electron microscopy at various intervals after intranasal inoculation with graded doses of phase I Bordetella bronchiseptica. In mice infected with a lethal dose (6 to 7 x 10(7) CFU), a remarkable rupture of the cell membranes of cilia and microvilli of the middle trachea was found on day I postinfection. The rupture of the membrane was observed over the entire tracheal epithelia, on day 2 after infection. The affected cilia were constricted at the transitional region and were broken off. In the ciliated cells the adherence of organisms to ciliary apexes and colonization in the interciliary spaces were also remarkable. In both the ciliated and nonciliated epithelial cells, the cytoplasmic vacuolation and pyknosis or karyorrehexis were also notable. In mice infected with one-tenth of the lethal dose, similar findings were seen, but appeared more slowly and the bacteria were not seen attaching to ciliary apexes. In mice receiving one-hundredth of the lethal dose, only mild cilial abnormality such as aggregation of cilia, and slight cytoplasmic vacuolation were found 6 days postinfection. Based on these findings, a possible mechanism of the ciliary damages produced by B. bronchiseptica was postulated.     

Electronic structure and molecular design of simplified polyimide systems

The electronic structures of newly designed polyimide systems (ethenetetracarboxylic 1,2:1,2-dianhydride-diaminoethyne (PI-A) and ethenetetracarboxylic 1,1:2,2-dianhydride-diaminoethyne(PI-B)) are studied in detail with respect to their optimized geometries on the basis of the one-dimensional tight-binding self-consistent field crystal-orbital method. The computational results have revealed that PI-B shows intriguing properties such as a very small band gap and a wide bandwidth near the frontier level, compared with PI-A and other polyimides. Since PI-B would be a promising candidate for a new electric conducting material, a reaction diagram for this polymer is also proposed.Also affiliated to Central Research Laboratories, Matsushita Electric Industrial Co., Moriguchi 570, Japan.     

A hyperthermostable pullulanase produced by an extreme thermophile,Bacillus flavocaldarius KP 1228, and evidence for the proline theory of increasing protein thermostability

Summary A cell-associated pullalanase (-dextrin 6-glucanohydrolase, EC 3.2.1.41) of an extreme thermophile, Bacillus flavocaldarius KP 1228, was purified to homogeneity. The molecular weight and isoelectric point were estimated to be about 55 000 and 7.0, respectively. The N-terminal sequence was Ala-Try-Tyr-Glu-Gly-Ala-Phe-Phe-Tyr-Gln-Ile-Phe-Pro-Asp-Tyr-Phe-Phe-Tyr-Ala-Gly-. The enzyme was most active at pH 6.3. The activities for 5% pullulan and 5% soluble starch were maximal at 75–80° C and at 80–85° C, respectively. The enzyme was stable up to 90° C for 10 min at pH 6.8. The enzyme had no antigenic determinants shared with pullulanases from the mesophiles Klebsiella pneumoniae and B. acidopullulyticus NCIB 11647. A comparison of amino acid composition demonstrated that the proline content increased greatly in a linear fashion with the rise in thermostability in the order K. pneumoniae B. acidopullulyticus B. flavocaldarius enzymes, as found with Bacillus oligo-1,6-glucosidases.Presented in part at the Annual Meeting of the Agricultural Chemical Society of Japan at Tokyo, April 2, 1987 (Abstracts, p 91)Offprint requests to: Y. Suzuki