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21.
Lymphocyte activation and serine-esterase induction following recombinant interleukin-2 infusion for lymphomas and acute leukaemias 总被引:3,自引:0,他引:3
Seah H. Lim Colin Worman Andrew Jewell Chris Tsakona Frank J. Giles Anthony Goldstone 《Cancer immunology, immunotherapy : CII》1991,33(2):133-137
Summary C57BL mice inoculated with radiation leukemia virus (RadLV) develop preleukemic cells long before the onset of leukemia. These cells are potentially immunogenic but fail to elicit an immune response in the host because of the appearance of virus-specific suppressor T cells. We have studied the effect of polysaccharide K (PSK) on the generation of RadLV-specific cell-mediated immune responses in vitro. Long-term exposure to PSK in culture potentiated the ability of immunized T cells to respond to a RadLV-induced lymphoma. It also abrogated the suppressive activity of suppressor T cells and simultaneously boosted the ability of reactive T cells to respond. The dual immunostimulating activity of PSK resulted in the generation of T cytotoxic lymphocytes that could lyse lymphoma cells in vitro. The results suggest that PSK could be used as a prophylactic immune response modifier in preleukemia. 相似文献
22.
Reaction of pyruvate kinase with the new nucleotide affinity labels 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 5'-diphosphate and 5'-triphosphate 总被引:1,自引:0,他引:1
Two new reactive nucleotides have been synthesized and characterized: 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 5'-diphosphate and 5'-triphosphate (8-BDB-TADP and 8-BDB-TATP). ADP or ATP was converted to 8-thio-ADP (-ATP) via 8-bromo-ADP (-ATP), followed by condensation with 1,4-dibromobutanedione. Rabbit muscle pyruvate kinase is inactivated by both reagents in a biphasic manner with an initial rapid loss of 75% activity, followed by a slow total inactivation. The initial fast reaction with both compounds exhibits nonlinear dependence on reagent concentration, indicating formation of a reversible enzyme-reagent complex prior to covalent attachment. The presence of the gamma-phosphoryl group improves the performance of the affinity label: KI values for the fast phase are similar (about 100 microM), whereas kmax for 8-BDB-TATP is about three times greater than that of 8-BDB-TADP (0.286 min-1 vs 0.0835 min-1). After an 80-min incubation with 175 microM of either reagent, about 2 mol/mol of subunit is incorporated with 76% inactivation caused by 8-BDB-TADP and 97% inactivation by 8-BDB-TATP. Loss of activity is prevented by substrates, with the best protection afforded by a combination of ATP, Mn2+, K+, and phosphoenolpyruvate. Reaction of pyruvate kinase with either compound in the presence of protecting ligands leads to incorporation of about 1 mol of reagent/mol of subunit with only about 15% loss of activity. These results suggest that 8-BDB-TADP and 8-BDB-TATP react with two groups on the enzyme, one of which is at or near the active site.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
23.
Parulekar SJ Semones GB Rolf MJ Lievense JC Lim HC 《Biotechnology and bioengineering》1986,28(5):700-710
Continuous cultures of Saccharomyces cerevisiae are known to exhibit oscillatory behavior in the oxidative region. Important findings of a series of experiments conducted to identify the causes for initiation of and the means for elimination of oscillations in these cultures are reported in this paper. These oscillations are seen to be connected to the growth kinetics of the microorganism and are induced at very low glucose concentrations and at dissolved oxygen (DO) levels that are neither high nor low (DO values between 20 and 78% air saturation at a dilution rate of 0.2 h(-1) and pH of 5.5 at 30 degrees C). The oscillatory behavior is encountered over a range of dilution rates (0.09-0.25 h(-1) at 30 degrees C for pH = 5.5 and DO = 50% air saturation). The oscillations can be eliminated by raising the DO level above a critical value or by lowering the DO level below a critical value. 相似文献
24.
Single crystals have been prepared of Paracoccus denitrificans amicyanin, a blue copper protein that serves as an electron acceptor for methylamine dehydrogenase. The crystals belong to the monoclinic space group P2(1), and have unit cell parameters a = 20.90 A, b = 56.61 A, c = 27.55 A and beta = 96.41. There is one molecule in the asymmetric unit. The crystals diffract to beyond 1.5 A resolution. 相似文献
25.
The structure of the capsular polysaccharide from Klebsiella K79 was determined by the techniques of methylation, periodate oxidation, beta-elimination, chromic acid oxidation, and partial hydrolysis. N.m.r. spectroscopy (1H and 13C) was used extensively to establish the nature of the anomeric linkages of the polysaccharide and of oligosaccharides derived through degradative procedures. The polysaccharide was found to have the heptasaccharide, "5 + 2" repeating unit: (Formula: see text). 相似文献
26.
27.
Sulfmyoglobin. Resonance Raman spectroscopic evidence for an iron-chlorin prosthetic group 总被引:1,自引:0,他引:1
L A Andersson T M Loehr A R Lim A G Mauk 《The Journal of biological chemistry》1984,259(24):15340-15349
The green heme protein sulfmyoglobin (SMb) has been suggested to contain a sulfur-modified iron chlorin prosthetic group. To evaluate this hypothesis, we have obtained high-frequency (greater than 1000 cm-1) resonance Raman spectra of both oxidized and reduced SMb with 457.9-, 488.0-, 514.5-, 568.2-, and 647.1-nm excitation. The SMb spectra are compared to those of native met- and deoxymyoglobin (Mb). Vibrational frequencies for SMb are generally similar to those of Mb, suggesting a high-spin state for both the Fe(III) and Fe(II) SMb species, as is typical of native Mb. However, major differences between SMb and Mb occur both for patterns of relative spectral intensities and for depolarization ratios. In particular, all B1g-depolarized porphyrin modes in the Mb spectra have become polarized, totally symmetric vibrational modes in the SMb spectra. These contrasts reflect a dramatic lowering of the effective symmetry for the SMb prosthetic group. Several new bands are observed in SMb spectra that are not present in spectra of either native Mb or iron protoporphyrin IX complexes. The observation of additional polarized bands flanking the oxidation state marker, V4, is of particular interest. In a parallel study, we compared the resonance Raman spectral properties of iron protoporphyrin IX-derived chlorins and metallo-octaethylchlorins with those of the analogous porphyrins: the chlorin spectra exhibited altered intensity patterns, an increased number of totally symmetric (polarized) vibrational bands, and several new vibrational bands, including one or two in the region of the oxidation state marker, V4. Thus, the resonance Raman spectral characteristics of SMb and metallo-chlorins are complementary and strongly support a chlorin prosthetic group for SMb. Furthermore, they establish testable criteria for investigating the prosthetic group structures of other green heme proteins by resonance Raman spectroscopy. 相似文献
28.
High-performance liquid chromatography of uroporphyrinogen and coproporphyrinogen isomers with amperometric detection. 总被引:1,自引:0,他引:1 下载免费PDF全文
A reversed-phase h.p.l.c. system, with an ODS-Hypersil column with acetonitrile or methanol in ammonium acetate buffer as mobile phase, is described for the separation of uro-and copro-porphyrinogen isomers. The porphyrinogens are detected amperometrically with sensitivity comparable with that of the fluorescent detection of porphyrins. The effects of pH, buffer concentration and organic modifiers on retention and resolution were studied. The method is suitable for both analytical and preparative separation of porphyrinogens. 相似文献
29.
30.
A reversed-phase system is described for the simultaneous isocratic separation of coproporphyrin I, II, III and IV isomers. The retention behaviour of coproporphyrin I and III is studied in detail. The method is suitable for both analytical and semi-preparative separation. 相似文献