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91.
P.C. Noordam A. Killian R.F.M. Oude Elferink J. de Gier 《Chemistry and physics of lipids》1982,31(2):191-204
Comparative studies on bilayer systems of saturated phosphatidylcholines and phosphatidylethanolamines revealed a maximum in ionic permeability in phosphatidylcholine bilayers at the temperature of the gel to liquid-crystalline phase transition but such an increase in permeability was not detectable in bilayers of phosphatidylethanolamine. Furthermore, it was found that at the phase transition temperature the phosphatidylcholine bilayers are subject to rapid hydrolysis by pancreatic phospholipase A2 whereas phosphatidylethanolamine bilayers are not. These differences are discussed in view of detailed information on the molecular organization in the gel and liquid crystalline phases of the two phospholipid classes. 相似文献
92.
Imre Mezö János Seprödi Judit Érchegyi István Teplán Magdolna Kovacs Bela Flerkó 《Peptides》1983,4(2):149-151
Inhibitory analogues of luteinizing hormone-releasing hormone (LH-RH) were prepared with formyl-D-Trp1, acetyl-D-Trp1, valeryl-D-Trp1, tartaryl-D-Trp1, diacetyl-tartaryl-D-Trp1, acetyl-Gly1, and acetyl-Sar1 successively replacing the position one in the analogue [D-Trp1, D-p-Cl-Phe2, D-Trp3, D-Phe6, D-Ala10]-LH-RH. The formyl-D-Trp1 and acetyl-D-Trp1 analogues yielded 100% blockade of ovulation at the 10 μg dose; the others were less potent and inhibited ovulation at the 50 μg dose. The inhibitory potency seems to correlate with the polarity of the acyl group. 相似文献
93.
Tunicamycin, an inhibitor of the asparagine-linked protein N-glycosylation, blocks the initiation of DNA synthesis in Swiss 3T3 cells stimulated by prostaglandin F2α alone or with insulin. This effect is exerted only when tunicamycin is added from 0 to 8 h after stimulation and it decreases the rate of entry into S phase. Blocking of labeled sugar incorporation to proteins occurs regardless of the time of PGF2α stimulation. In contrast tunicamicin does not inhibit protein synthesis. These results suggest that N-glycoprotein synthesis early during the prereplicative phase is an important event controlling the mitogenic action of PGF2α 相似文献
94.
95.
K. M. Dziegielewska W. M. Brown C. C. Gould N. Matthews J. E. C. Sedgwick N. R. Saunders 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(2):168-171
Summary Fetuin is a plasma protein present in high concentrations during fetal development in animals of the order Artiodactyla. Its role is not known. The human homologue of fetuin — 2HS glycoprotein — has been shown to be a negative acute phase protein in adult plasma. In the present study, the concentration of fetuin was measured in the serum of healthy cattle (Bovis bovis) and in animals with various injuries and inflammatory disorders. The levels were decreased by 30% in pregnancy but increased up to 10-fold in some trauma cases. A significant negative correlation between the concentrations of fetuin and albumin has also been found. Thus, fetuin appears to be a positive acute phase protein in cattle.Abbreviations 2HS
2HS glycoprotein
- AP
acute phase 相似文献
96.
An experimental investigation of the low hydration phase properties of phospholipid mixtures is described. 2H (D2O) NMR, X-ray diffraction and differential scanning calorimetry have been used to elucidate the phase properties of mixtures of the mixed chain phospholipids palmitoyloleoylphosphatidylcholine (POPC) and palmitoyloleoylphosphatidylethanolamine (POPE). At 10% hydration pure POPE exhibited a HII phase above 330 K, a fluid lamellar phase below 315 K, and a minimally hydrated crystalline phase below 300 K. For the 1:1 mixture, the samples exhibited only gel or fluid phases between 270 K and 360 K for hydrations in the range 15% to 30%. Below 15% hydration the mixture exhibited two fluid phases with different repeat spacings, as predicted previously. 相似文献
97.
Two- and three-phase mixing studies were carried out in a 44-L concentric draft tube gas-lift fermentor. It was proposed to use the fermentor for the production of solvents using immobilized bacteria. Bubble size, gas holdup, liquid velocities, circulation, and mixing times were determined for various superficial gas velocities in distilled water, starch, carboxymethyl cellulose, and ethanol solutions. The observed trends for two phase mixing were similar to other studies but the results were found to be more sensitive to liquid properties. This was possibly due to the large value of downcomer to riser area used in this study. Mixing in three phases highlighted the difficulty in predicting the effect of adding solids to the gas-liquid system. Results showed that the gas-lift fermentor was ideally suited to dealing with three phases but more work is necessary before accurate models can be developed to account for the effect of solids. 相似文献
98.
Cellulose-based stationary phases are known to be very efficient and versatile chiral sorbents for the chromatographic resolution of racemates. Except for microcrystalline cellulose triacetate (CTA I), basically all other cellulose-based phases have been prepared by coating of ca. 20% weight polymer on a wide pore silica gel used as a carrier. In this work we describe the preparation of benzoylcellulose (TBC) beads in the pure polymeric form (without inorganic carrier) from an emulsion of the organic polymer. The new material has been fully characterized and used as a chiral stationary phase for the resolution of various classes of racemic compounds such as benzylic alcohols or acetate derivatives of aliphatic alcohols and diols. The structural variety of the separated solutes as well as the irrational influence of the aromatic substituent in different classes of aryl compounds suggest that multiple interaction sites are involved in the complexation, making a prediction of the separation difficult. The benzoyl cellulose beads exhibit a very high loading capacity, which is particularly useful for preparative purposes as demonstrated for selected examples. 相似文献
99.
Li-Chun Huang Cheng-Kuo Hsiao Shu-Huey Lee Bau-Lian Huang Toshio Murashige 《In vitro cellular & developmental biology. Plant》1992,28(1):30-32
Summary Repeated grafting of 0.2-cm shoot tips from fruiting-age trees ofCitrus reticulata Blanco ‘Ponkan’ mandarin andC. sinensis Osbeck ‘Liu Tseng’ sweet orange onto freshly germinated ‘Troyer’ citrange [Poncirus trifoliata (L.) Raf. X.C. sinensis Osbeck] seedlings in vitro resulted in progressive restoration of rooting competence and vigor of regenerated roots and shoots.
The restored traits were retained through the course of the investigation and suggested a phase reversal phenomenon. 相似文献
100.
Partitioning in dextran-poly(ethylene glycol) aqueous two-phase systems is an established method for the separation of biomaterials. Size and surface properties are generally regarded as parameters which contribute to the determination of the materials' partition coefficients, K. While molecular weight or surface area can be one of the determinants of the K value of biomaterials in the size range of macromolecules to very small particulates (e.g. some viruses), partitioning liposomes of identical surface properties and different but distinct sizes indicate that surface areas greater than about 0.2 μm2 do not affect the K value obtained. Analysis of available partitioning data of much larger particulates (i.e. cells) reveals that surface properties per unit area outweigh surface area per se in determining the K value in non-charge-sensitive, charge-sensitive and biospecific affinity phase systems. 相似文献