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91.
G N La Mar T Jue K Nagai K M Smith Y Yamamoto R J Kauten V Thanabal K C Langry R K Pandey H K Leung 《Biochimica et biophysica acta》1988,952(2):131-141
The heme methyl and vinyl alpha-proton signals have been assigned in low-spin ferric cyanide and azide ligated derivatives of the intact tetramer of hemoglobin A, as well as the isolated chains, by reconstituting the proteins with selectively deuterated hemins. For the hemoglobin cyanide tetramer, assignment to individual subunits was effected by forming hybrid hemoglobins possessing isotope-labeled hemins in only one type of subunit. The heme methyl contact shift pattern has 1-methyl and 5-methyl shifts furthest downfield in both chains and the individual subunits of the intact hemoglobin in both the cyanide- and azide-ligated species, which is consistent with a dominant rhombic perturbation due to the proximal His-F8 imidazole pi bonding in the known structure for human adult hemoglobin. The individual chain and subunit assignments confirm that the detailed electronic/magnetic properties of the heme pocket are essentially unaltered upon assembling the R-state tetramer from the isolated subunits. 相似文献
92.
T Onishi S Morimoto H Yamamoto S Takamoto K Fukuo S Imanaka T Hironaka Y Okada R Matoba Y Kumahara 《Endocrinologia japonica》1988,35(6):925-931
A male patient with hypogonadotropic hypogonadism has been treated by pulsatile administration lf luteinizing hormone-releasing hormone (LHRH) (20-25 micrograms, every 2 hours, sc) for 4 years 6 months. His plasma testosterone (T) concentration began to increase after 4 weeks of treatment and reached the normal range in week 5. He showed complete secondary sexual development after 1 year of treatment. His sperm count was normalized after 1 year of treatment. He was married after 29 months of therapy, and has a healthy male child. Blood type tests showed his paternity of the child. During the long duration of pulsatile LHRH therapy, his gonadotropin secretion has been stimulated by LHRH and his T level has been maintained with no observable side effects. There are no other reports of patients treated by pulsatile LHRH injection for such a long duration, but finding in this patient indicated that long-term pulsatile LHRH therapy is a useful and safe method for treatment of hypothalamic hypogonadotropic hypogonadism. 相似文献
93.
The 6R-oxygenase activity of arachidonate 5-lipoxygenase purified from porcine leukocytes 总被引:1,自引:0,他引:1
Arachidonate 5-lipoxygenase purified from porcine leukocytes was incubated with (5S)-hydroperoxy-6,8,11,14-eicosatetraenoic acid. In addition to degradation products of leukotriene A4 (6-trans-leukotriene B4 and its 12-epimer and others), (5S,6R)-dihydroperoxy-7,9,11,14-eicosatetraenoic acid was produced as a major product especially when the incubation was performed on ice rather than at room temperature. The amount of the (5S,6R)-dihydroperoxy acid was close to the total amount of leukotriene A4 degradation products. Under the anaerobic condition, production of the (5S,6R)-dihydroperoxy acid was markedly reduced. 5-Hydroxy-6,8,11,14-eicosatetraenoic acid could be a substrate of the enzyme and was transformed predominantly to a compound identified as (5S)-hydroxy-(6R)-hydroperoxy-7,9-trans-11,14-cis-eicosatetraenoic acid at about 1-2% rate of arachidonate 5-oxygenation. These findings indicated that the purified 5-lipoxygenase exhibited a 6R-oxygenase activity with (5S)-hydroxy and (5S)-hydroperoxy acids as substrates. The 6R-oxygenase activity, like the leukotriene A synthase activity, was presumed to be an integral part of 5-lipoxygenase because it required calcium and ATP and was affected by selective 5-lipoxygenase inhibitors. 相似文献
94.
K Hatanaka H Tanishita H Ishibashi-Ueda A Yamamoto 《Biochimica et biophysica acta》1986,878(3):440-445
Approximately 70% of the W/WV mice lacking mast cells due to a genetic defect showed hypertriglyceridemia combined with hypercholesterolemia. Increases of various magnitudes in chylomicrons, very-low-density lipoprotein, and intermediate-density lipoprotein were observed in the plasma of W/WV mice compared to those in the plasma of congenic normal mice. The increase in these lipoproteins was seen even in normolipidemic W/WV mice. Activities of both lipoprotein lipase and hepatic triacylglycerol lipase in the plasma after heparin injection were markedly lower in the W/WV mice than in the congenic normal mice, although activities of both lipoprotein lipase in the heart and adipose tissue and hepatic triacylglycerol lipase in the liver were not decreased. These results suggest that the W/WV mice have genetic defects in one or more of the following: secretion of both lipases from their synthesising cells, transport to the endothelium, and anchoring to the endothelial surface. Heparin deficiency in these mice may be responsible for the impairment and, thereby, may partially contribute to the hyperlipidemia. 相似文献
95.
M Suzuki K Yoshida T Sakurada N Kaise K Kaise H Fukazawa T Nomura Y Itagaki K Yonemitsu M Yamamoto 《Endocrinologia japonica》1986,33(1):37-42
We studied the effect of the state of the thyroid on T4 monodeiodination in the rat placenta, and it was compared with those in the liver and kidney. The tissues, maternal serum, and amniotic fluid were obtained from pregnant rats. The tissues were homogenized in cold 50 mM Tris-HCl buffer, pH 7.5. The homogenate (1 mg protein) was incubated at 37 degrees C for 60 min with 1 microgram T4 in the presence of 5 mM DTT. The T3 and reverse T3 generated in the reaction mixture were extracted into cold ethanol and measured by RIAs. The conversion of T4 to reverse T3 in rat placenta was not significantly changed in MMI-induced hypothyroidism or T4 induced hyperthyroidism. On the other hand, conversion of T4 to T3 in the liver and kidney were changed in parallel with the thyroid state. The concentration of reverse T3 in the amniotic fluid was increased in accordance with the increase in the maternal serum T4 concentration. These results indicate that the placental T4 inner ring deiodination is not affected by the thyroid state, and that the change in the amniotic fluid reverse T3 concentration in this study is mainly dependent upon the change in maternal thyroid function. 相似文献
96.
Nickel(II)-reconstituted hemoglobin (NiHb) and myoglobin (NiMb) and model Ni porphyrins have been investigated by Soret-resonance Raman difference spectroscopy. Two sets of frequencies for the oxidation-state and core-size marker lines in the region from 1300 to 1700 cm-1 indicate two distinct sites in NiHb. Only one of these sites is evident in the Raman spectra of NiMb. This result is consistent with the UV-visible absorption spectrum of NiHb, which shows two Soret bands at 397 and 420 nm and one Soret at 424 nm for NiMb. Excitation at the blue Soret component of NiHb with 406.7-nm laser radiation preferentially enhances the set of Raman marker lines typical of Ni-protoporphyrin IX [Ni(ProtoP )] in noncoordinating solvents. The wavelength of the blue Soret component and the Raman spectrum indicate four-coordination for this site in NiHb. Laser excitation in the red Soret band enhances a set of lines whose frequencies are compatible with neither four- nor six-coordinate frequencies but are intermediate between the two. The red Soret band of the proteins is also considerably less red shifted than six-coordinate Ni-porphyrin models. These results suggest that Ni in the second site possesses a single axial ligand. Raman spectra of 64Ni-reconstituted and natural abundance Ni-reconstituted hemoglobins, obtained simultaneously in a Raman difference spectrometer, have identified the Ni-ligand stretch at 236 cm-1. The line shifts to 229 cm-1 for the 64Ni-reconstituted Hb. For a pure Ni-ligand stretch a 10-cm-1 shift would be predicted.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
97.
Ca2+ compartments in saponin-skinned cultured vascular smooth muscle cells 总被引:2,自引:0,他引:2
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A method for saponin skinning of primary cultured rat aortic smooth muscle cells was established. The saponin-treated cells could be stained with trypan blue and incorporated more 45Ca2+ than the nontreated cells under the same conditions. At low free Ca2+ concentration, greater than 85% of 45Ca2+ uptake into the skinned cells was dependent on the extracellularly supplied MgATP. In the intact cells, both caffeine and norepinephrine increased 45Ca2+ efflux. In the skinned cells, caffeine increased 45Ca2+ efflux, whereas norepinephrine did not. The caffeine-releasable 45Ca2+ uptake fraction in the skinned cells appeared at 3 X 10(-7) M Ca2+, increased gradually with the increase in free Ca2+ concentration, and reached a plateau at 1 X 10(-5) M Ca2+. The 45Ca2+ uptake fraction, which was significantly suppressed by sodium azide, appeared at 1 X 10(-5) M Ca2+ and increased monotonically with increasing free Ca2+ concentration. The results suggest that the caffeine-sensitive Ca2+ store, presumably the sarcoplasmic reticulum, plays a physiological role by releasing Ca2+ in response to norepinephrine or caffeine and by buffering excessive Ca2+. The 45Ca2+ uptake by mitochondria appears too insensitive to be important under physiological conditions. 相似文献
98.
A sensitive and specific enzyme-linked immunosorbent assay (ELISA) for cholecystokinin octapeptide sulfate (CCK-8S) has been developed using N-terminal specific antibody for CCK-8S. In this assay CCK-8S coupled with poly-L-Glu (CCK-poly-Glu), which is adsorbed on a solid phase, competes with CCK-8S for the binding sites of rabbit anti-CCK antibody, and the complex of the immobilized antibody and CCK-poly-Glu is measured using goat anti-rabbit immunoglobulin G conjugated with horseradish peroxidase. The total time for completion of the assay is less than 24 h. Near 50% bound levels, the intraassay coefficient of variation is 5.2-6.2% and the interassay coefficient of variation is 5.9-8.5%. This assay is sensitive enough to detect 9 pg of CCK-8S, and the data from rat brain regions using this ELISA are very similar to the data from those using radioimmunoassay (RIA). Therefore, this ELISA is simpler and more rapid in comparison with conventional RIA. In the preliminary experiments, we applied this method for determination of CCK content in the brain regions of adult rats treated with 6-hydroxy-dopamine or in newborn rats subjected to anoxia, and showed that this system is applicable to detection of changes of endogenous CCK content. 相似文献
99.
Induction of SOS functions by nitrogen dioxide in Escherichia coli with different DNA-repair capacities 总被引:1,自引:0,他引:1
The effect of gaseous nitrogen dioxide (NO2) on cytotoxicity, induction of synthesis of UmuC and RecA proteins, and mutagenesis was studied in Escherichia coli strains with different capacities of DNA repair. Gaseous NO2 (90, 180 microliter/l) killed Escherichia coli. The recA mutant was most sensitive, the lexA mutant moderately sensitive, and the uvrA mutant and the wild-type the least sensitive. When 90 microliter/l NO2 gas was bubbled into bacterial suspensions for 30 min at a flow rate of 100 ml/min, the induction of umuC gene expression increased in the wild-type strain. NO2 also induced the recA gene expression in the wild-type strain. The synthesis of neither RecA nor UmuC proteins was induced in the recA and lexA mutants. We further investigated the NO2 mutagenesis in the cells treated with bubbling of NO2 gas. NO2 caused mutation to Trp+ of WP2. 相似文献
100.
The absorption spectrum of native pea chromatin solubilizedunder minimal shearing conditions changed with increasing Ca2+concentration; the ratio of maximum to minimum absorption decreasedand the maximum absorption peak shifted to a longer wavelength.The concentration of Ca2+ to cause half complete sedimentationof chromatin was much lower for the solubilized native chromatin(more condensed and larger in size) than for the sonicated chromatin(less condensed and smaller in size). Solubilized native chromatinshowed a two-step melting profile in the absence of Ca2+. In the presence of Ca2+ the two Tms disappeared and a new higherTm appeared. Template activity of solubilized native chromatinincreased 3-fold upon dispersion and fragmentation by sonication.Addition of a small amount of ethylene glycol-bis (ß-aminoethylether)-N, N'-tetraacetic acid (EGTA) promoted the template activityof solubilized native chromatin, but not that of sonicated ordenatured DNA. The effect of EGTA was reversed by Ca2+. Thechromatin reconstituted in the presence of EGTA showed a lowerTm than the chromatin reconstituted in the presence of Ca2+.The relationship between chromatin structure and its templateactivity is discussed in relation to Ca2+. (Received August 12, 1985; Accepted December 7, 1985) 相似文献