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991.
Kazuhiro Osada Kazuhiko Nagira Kiichiro Teruya Hirofumi Tachibana Sanetaka Shirahata Hiroki Murakami 《Biotherapy》1993,7(2):115-123
A fermented milk, Kefir, contains an active substance which enhances IFN- secretion of a human osteosarcoma line MG-63 treated with a chemical inducer, poly I: poly C. The active substance in the fermented milk was identified to be sphingomyelin (SpM) by a combined use of a fast atom bombardment mass spectrometry (FAB-MS) and a fast atom bombardment tandem mass spectrometry (FAB-MS/MS). SpM from fermented milk (F-SpM) was a mixture of four molecular species of SpMs having C21-, C22-, C23- and C24-fatty acids. F-SpM enhanced the IFN secretion 14 times, SpMs from other sources also enhanced moderately (2–3 times). Sphingosine and lysosphingomyelin also enhanced the activity but ceramide and cerebroside did not.Abbreviations IFN-
interferon-
- SpM
sphingomyelin
- Lyso-SpM
lysosphingomyelin
- SpS
sphingosine
- FAB-MS
fast atom bombardment mass spectrometry
- FAB-MS/MS
fast atom bombardment tandem mass spectrometry 相似文献
992.
Makoto Murakami 《Journal of Protein Chemistry》1993,12(6):783-789
Various reports have described that amino acid substitutions can alter substrate, positional, inhibitory, and target gene specificities of proteins. By using the method of Chou and Fasman, the present work predicts that critical amino acids for converting these specificities are located around -turns. Residues responsible for the alterations of substrate specificities of trypsin,l-lactate dehydrogenase, aspartate aminotransferase, -lactamase, and cytochrome P-450 are found to exist within regions predicted as -turns. The ratios of hydroxylation and oxygenation positions of substrates by cytochrome P-450 and lipoxygenase, respectively, are varied by changes of the protein structures, probably around turn conformations. Inhibitory specificities of bovine pancreatic trypsin inhibitor and 1-antitrypsin and target gene specificity of glucocorticoid receptor are converted by changing turn structures. Occurrence of -turn probabilities can be predicted around the amino acid alteration positions of an evolutionally antecedent protein of a nylon degradation enzyme. These findings will have relevance to work on protein engineering and enzyme evolution. 相似文献
993.
The effect of the Cyt b6-f redox state on the PSI formationwas examined with the cyanophyte Synechocystis PCC 6714 by usinga Q-cycle inhibitor, HQNO (2-n-heptyl-4-hydroxyquinoline N-oxide).HQNO inhibited the rapid reduction of flash-oxidized Cyt f,the reaction correlating with the stimulation of PSI formation,on one hand, and accumulated reduced Cyt b6, on the other, indicatingthat the electron flow in the Q-cycle correlates with regulationof PSI synthesis. HQNO also inhibited the stimulation of PSIformation under PSII light, resulting in a low PSI/PSII ratioeven under PSII light, while the PSI formation under PSI lightwas not suppressed by HQNO. Simultaneous inhibition of Cyt b6oxidation through the Q-cycle and the stimulated PSI formationby HQNO suggests that an HQNO-sensitive Cyt b6 oxidation isinvolved in the mechanism of monitoring the state of electrontransport system for regulation of PSI formation. (Received March 3, 1993; Accepted August 9, 1993) 相似文献
994.
Interstitial cells in the pineal gland of the rat were characterized immunocytochemically using the monoclonal antibodies MRC OX-42 and ED1 for macrophages/microglia, and MRC OX-6, which recognizes major histocompatibility complex (MHC) class II antigen. A polyclonal antibody against GFAP was used to identify astrocytes. Cells immunopositive for OX-42 and/or ED1 were distributed throughout the gland; they extended processes primarily along the perivascular spaces and occasionally within the parenchyma of the gland. Ultrastructurally, these OX-42-positive cells were characterized by a nucleus with sparse heterochromatin and cytoplasmic vacuoles/lysosomes. Cells expressing MHC class II antigen had a distribution and morphology similar to OX-42-immunopositive cells, suggesting that pineal macrophages/microglia play a role as antigen-presenting cells. GFAP-positive astrocytes were concentrated at the proximal end of the pineal where the pineal stalk enters the gland. The occurrence of antigenpresenting cells in the circumventricular neuroendocrine gland has important functional implications as these cells may be mediators of neuroimmunomodulatory mechanisms, and involved in certain disease states such as autoimmune pinealitis. 相似文献
995.
The effect of lyso-PAF on ciliated cells was investigated in vitro. Normal mucosa was surgically obtained from human paranasal sinuses and incubated in the form of tissue culture. Ciliated epithelium was magnified under an inverted microscope, and ciliary movement was photo-electrically measured. Ciliary activity was significantly inhibited by 10(-8) M lyso-PAF and could be restored. The effect of lyso-PAF was completely blocked by CV-6209, a specific PAF antagonist. The PAF concentration in the incubation medium of lyso-PAF was determined by radioimmunoassay, because PAF is a well known inhibitor of ciliary activity. PAF gradually increased and after 20 min reached its maximal level. These findings indicated the existence of an enzyme in the paranasal sinus mucosa, by which lyso-PAF is converted to PAF, and that lyso-PAF can inhibit ciliary activity by means of PAF. 相似文献
996.
Bovine and goat alpha-lactalbumins were substituted with 113Cd(II) or Mn(II) at the strong calcium site [Murakami, K., Andree, P.J., & Berliner, L.J. (1982) Biochemistry 21, 5488-5494] and studied by 113 Cd NMR and electron spin resonance. The 113Cd chemical shifts were in the -80 to -85 ppm range vs. Cd(ClO4)2, which was almost identical with that found for several nearly octahedral (oxygen-coordinated) calcium binding proteins such as calmodulin, parvalbumin, and troponin C. The electron spin resonance spectra of bound Mn(II)-alpha-lactalbumin complexes at 9 or 35 GHz were also confirmatory of a highly symmetric (cubic) environment around the Mn(II) with only slight distortions. The near identity of this site in alpha-lactalbumin to those of calcium binding proteins containing an "EF hand domain" was remarkable despite the absence of such a domain sequence in the alpha-lactalbumin structure. 相似文献
997.
Intracellular pH determination by a 31P-NMR technique. The second dissociation constant of phosphoric acid in a biological system 总被引:1,自引:0,他引:1
Y Seo M Murakami H Watari Y Imai K Yoshizaki H Nishikawa T Morimoto 《Journal of biochemistry》1983,94(3):729-734
To evaluate the accuracy of pH determination by 31P-NMR, factors which influence the pK value of phosphate were appraised on the basis of the titration of 1 mM phosphate buffer solution. When the method is used for the determination of cytoplasmic pH, ionic strength is the major factor causing shifts of apparent pK (pK') value, and the magnitude of the shift can be predicted from the ionic strength calculated by means of the Debye-Hückel equation. Ions (Na+, K+, Mg2+, and Ca2+) and salivary protein affected the pK' value by 0.1 to 0.3 units in solution with a given ionic strength depending on the species of ion. The form of the titration curve varied with temperature. Based on these results, the value of 6.75 was obtained with the uncertainty of 0.12 for the intracellular pK' of frog muscle at 24 degrees C. 相似文献
998.
K Murakami 《Journal of biochemistry》1979,86(5):1331-1336
The kinetic and molecular properties of AMP deaminase [AMP aminohydrolase, EC 3.5.4.6] purified from baker's yeast (saccharomyces cerevisiae) were investigated. The enzyme was activated by ATP and dATP, but inhibited by Pi and GTP in an allosteric manner. Alkali metal ions and alkaline earth metal ions activated the enzyme to various extent. Kinetic negative cooperativity was observed in the binding of nucleoside triphosphates. Kinetic analysis showed that the number of interaction sites for AMP (substrate) and Pi (inhibitor) is two each per enzyme molecule. The molecular weight of the native enzyme was estimated to be 360,000 by sedimentation equilibrium studies. On polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the enzyme gave a single polypeptide band with a molecular weight of 83,000, suggesting that the native enzyme has a tetrameric structure. Baker's yeast AMP deaminase was concluded to consist of two "promoter" units which each consist of two polypeptide chains with identical molecular weight. 相似文献
999.
The serum estradiol concentration and bone mineral content of the right radius were determined in 34 postmenopausal females. Regression analysis showed a significant positive correlation between the serum estradiol concentration and bone mineral content of the right radius (r=0.477, p less than 0.01). These results support the view that the decreased level of serum estrogens is one of the major factors involved in the loss of bone mass with age. 相似文献
1000.
The flow measurement of each component in each compartment is important in works on transport phenomena in a biological system. The method of flow measurement was studied adopting the capacitor concept derived from network thermodynamics.A biologically active component i in a compartment is defined as follows, where the total quantity ni consists of a measurable form ni (free form, conc. c1) and concealed form n2 (conc, c2). Capacitor for the species i of a compartment is defined as follows, , Thus flow of each component is expressed as, , Method of determination of capacitor coefficients A and B by titration experiment was also considered. For an experimental case, the capacitance for H+ of blood compartment was determined. The relationship between the capacitor concept and the buffer value of Van Slyke was discussed. 相似文献