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1.
D E Sok C O Han W R Shieh B N Zhou C J Sih 《Biochemical and biophysical research communications》1982,104(4):1363-1370
Human leukocytes converted [3H]-(S)-15-HPETE into [3H]-14,15-LTA. Rat basophilic leukemia cells transformed 14,15-LTA into two bioactive C(14)-S-linked peptides, which have been characterized as 15(S)-hydroxy-14(R)-S-glutathionyl-5,8,10,12-icosatetraenoic acid and 15-(S)-hydroxy-14(R)-S-cysteinylglycyl-5,8,10,12-icosatetraenoic acid by comparison with synthetic specimens. 相似文献
2.
Kelvin W. Gee Frederick J. Ehlert Henry I. Yamamura 《Biochemical and biophysical research communications》1982,106(4):1134-1140
The influence of GABA on the affinity of flunitrazepam (FLU) for benzodiazepine receptor subtypes (type I and II) was studied by measurement of the competitive inhibition of [3H]FLU and [3H]propyl beta-carboline-3-carboxylate ([3H]PCC) binding. When assays were carried out at 0°C using a low concentration (0.040 nM) of [3H]PCC so that the type I receptors were selectively labelled, no significant effect of GABA (10?4 M) on the competition curve was detected. In contrast, when assays were carried out at 0°C using [3H]FLU or a high concentration of [3H]PCC to achieve [3H]ligand receptor occupancy of both type I and type II receptors, GABA (10?4 M) caused a significant increase in the affinity of FLU as measured by and competition experiments. Collectively, these data suggest that the influence of GABA on benzodiazepine receptor binding is mediated, primarily, by the type II receptor. It was also noted that the competition curve had a Hill coefficient of approximately 1 at 37°C as compared to the results of experiments at 0°C during which a Hill coefficient of approximately 0.7 was calculated. 相似文献
3.
4.
《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,677(2):326-329
Labelled shikimic acid was efficiently incorporated into the aniline moiety of , a characteristic aromatic compound of the common mushroom, Agaricus bisporus. Incubations with [3-3H]- and [1,6-14C]shikimic acid clearly proved that the amination of shikimic acid occurs at its 4-position during the biosynthesis of . 相似文献
5.
Timothy S. Gaginella Thomas J. Rimele Thomas M. ODorisio Robert J. Dorff 《Life sciences》1980,26(19):1599-1608
Muscarinic receptors in the smooth muscle of the cat pylorus (pyloric sphincter) were identified by binding of the ligand (±) [3H]-quinuclidinyl benzilate ([3H]-QNB). Receptor related binding of [3H]-QNB reached steady-state in thirty minutes at 37°C, was saturable, showed pharmacologic specificity and was stereoselective. An apparent equilibrium dissociation constant, KD, of 1.9 ± 0.3 nM and maximum receptor concentration of 122 ± 13 femtomoles per mg of protein (means ± S.E.M.) were determined from Scatchard plots of [3H]-QNB binding. Hill coefficients of 0.99 and 1.01 indicated the absence of cooperative interactions. The muscarinic antagonists atropine and propantheline inhibited binding with IC50 values in the nanomolar range, whereas bethanechol was over four orders of magnitude less potent. Noncholinergic agents had little or no effect on [3H]-QNB binding. The isomer of QNB was about seventy times more effective at inhibiting binding than its isomer while benzetimide was greater than two thousand fold more active than benzetimide. The isomers of another anticholinergic compound, tropicamide, also competed for [3H]-QNB binding sites in a stereoselective manner, the isomer being eighty-five times more potent than the isomer. 相似文献
6.
The effects of endometrium on metabolism of [3H]-arachidonic acid ([3H]-AA) by bovine blastocysts recovered on day 19 postmating were studied . Blastocysts (n = 12) and endometrial slices were assigned to four incubation groups. In group 1, blastocysts were incubated alone; group 2, endometrial slices were incubated alone; group 3, blastocysts were incubated with endometrial slices; group 4, blastocysts were incubated in 7.5 ml fresh incubation medium plus 7.5 ml frozen-thawed medium from endometrial incubations. In all groups, tissues were incubated in 15 ml modified minimum essential medium (MEM) containing 5 μCi of [3H]-AA and 200 μg radioinert arachidonic acid for 24 h at 37°C in an atmosphere of 50% N2:45% O2:5% CO2. For incubation controls, 5 μCi of [3H]-AA were added to 15 ml MEM and incubated at the same time as tissues from each cow. To evaluate metabolism of [3H]-AA, [3H]-AA and its metabolites were extracted from aliquots of MEM and separated on columns of Sephadex LH-20. Most (78.3 ± 3.2%) of the radioactivity (dpm) in the incubation controls was recovered as [3H]-AA, indicating that there was little breakdown of [3H]-AA in the absence of tissue. Blastocysts produced compounds that migrated with [3H]-13,14-dihydro-15-keto-PGF2α ([2H]-PGFM), [3H]-PGE2 and [3H]-PGF2α. Endometrial slices metabolized very little of the [3H]-AA. Data from groups 1 and 4 were combined (group ) for analysis because the distribution of dpm did not differ between the two groups. In group 3, blastocysts and endometrial slices incubated together tended(P<.10) to produced more [3H]-PGE2 than did group , there tended to be less (P<.10)_[3H]-PGF2α, and there was more (P<.05) [3H]-PGFM than in group . Neither endometrial secretions nor endometrial slices altered the proportion of [3H]-AA metabolized by blastocysts. Endometrial slices appear capable of metabolizing [3H]-PGF2α synthesized by blastocysts, and capable of directing blastocyst metabolism of [3H]-AA away from synthesis of [3H]-PGF2α and toward synthesis of [3H]-PGE2. It is postulated that the endometrium has an important role in regulating the amounts and ratios of prostaglandins in th uterine lumen during early prenancy in cows. 相似文献
7.
D.C. Anderson Steven C. King Stanley M. Parsons 《Biochemical and biophysical research communications》1981,103(2):422-428
Cholinergic synaptic vesicles isolated from the electric organ of are confirmed to exhibit energy-linked uptake of [3H] acetylcholine. [3H]Acetylcholine is concentrated in the vesicles by a factor of 10–14 in the presence of MgATP and bicarbonate. This active uptake can be completely inhibited by the mitochondrial uncouplers 3--butyl-5-Cl-2′-Cl-4′-nitro-salicylanilide (S-13) and -nitrophenol. The vesicle-associated ATPase is stimulated by S-13 in the same concentration range which inhibits [3H]acetylcholine active uptake. The ATPase also is stimulated by valinomycin. Both S-13 and valinomycin effects are independent of exogenous Ca2+. Thus, a proton gradient generated by the vesicle-associated ATPase appears to be coupled to active [3H]acetylcholine uptake. 相似文献
8.
Benzodiazepine receptors were labeled with [3H] diazepam following intravenous injection in rats. Binding of [3H] diazepam to rat forebrain membranes was displaceable by co-injection of clonazepam or the pharmacologically active enantiomers of two benzodiazepines, B9 and B10, but was not displaced by equal doses of the pharmacologically in-active enantiomers. Binding of [3H] diazepam was bserved in kidney, liver, and abdominal muscle, but was not stereospecifically diplaced in any peripheral tissue studied. The regional distribution of benzodiazepine receptors in brain was uneven, with specific [3H] diazepam binding being highest in the cerebral cortex and lowest in the ponsmedulla. Preliminary studies of the subcellular distribution of [3H] diazepam binding demonstrated highest specific binding to synaptosomal membranes. These data demonstrate the feasibility of labeling benzodiazepine receptors in rat brain . 相似文献
9.
We have investigated the catabolism of [3H] histamine (HA), after intraventricular (i.vt.) administration, in brains of the audiogenic seizure susceptible (SS) and resistant (SR) deermouse . Brains of SS mice had lower endogenous HA levels and contained less [3H]-HA 20, 60 and 300 sec after i.vt. [3H]-HA than did brains of SR deermice. Twenty sec after [3H]-HA, brain [3H] methylhistamine (MeHA) levels and the resulting MeHA conversion index were found to be increased in the SS animals while later, at 60 and 300 sec, these parameters were found to be decreased. There were no SS-SR differences in the levels of brain [3H] methylimidazoleacetic acid. The data indicate that SS deermice catabolize exogenous HA, at least initially, more rapidly than their SR counterparts, confirming a like result noted immediately prior to seizure activity elicited by the administration of L-methionine-dl-sulfoximine in . 相似文献
10.
[3H]Flunitrazepam was used to characterize benzodiazepine binding sites in human brain. The benzodiazepine binding sites exhibited high affinity, pharmacological specificity and saturability in their binding of [3H]flunitrazepam. The dissociation constant (KD) of [3H]flunitrazepam binding was determined by three different methods and found to be in the range of 2–3 nM. The potency of several benzodiazepine analogs to inhibit specific [3H]-flunitrazepam binding correlated well with their potency in several human and animal tests. The density of [3H]-flunitrazepam binding sites was highest in the cerebrocortical and rhinencephalic areas, intermediate in the cerebellum, and lowest in the brain stem and commissural tracts. 相似文献
11.
Results are presented on the stability of high specific activity [uridylate-5,6-3H]polyuridylic acid and [adenylate-2,8-3H]polyadenylic acid stored under various conditions. Polyacrylamide disc gel electrophoresis in the presence of SDS was used to assess qualitatively the change in molecular weight distribution of the polynucleotides stored under different conditions. Products stored for a period of months in ethanol; water solution [1:1, ] were found to have a significantly slower rate of decomposition than polynucleotides stored in frozen aqueous solution or as lyophilized solid. 相似文献
12.
Acetylcholine stimulates hydrolysis of 32 P-labeled phosphatidic acid in guinea pig synaptosomes 总被引:3,自引:0,他引:3
[3H]-inositol or [3H]-arachidonate was injected intracerebrally into guinea pigs. Labeled nerve endings were incubated with Ach1 or CCh, both of which stimulate labeling of PhA and PhI from 32Pi by > 100% and 70% respectively. Their addition did not affect the labeled phosphatidyl-[3H]-inositol or [3H]-arachidonyl-diglyceride and -PhI. Enhanced hydrolysis of [3H]-inositol-PhiP and -PhIP2 in the presence of ACh, CCh or choline was not reversed by atropine. In a two-step experiment, PhA was labeled with 32Pi, and DNP was added to block further formation. Addition of ACh stimulated an atropine-sensitive in [32P]-PhA. 相似文献
13.
[3 H] Estradiol-17β-succinyl bovine serum albumin conjugate ([3H]-E2-BSA) was synthesized with a specific activity of 1.92 × 107 cts/min/mg. The conjugate was administered iv to ovariectomized rats and the quantity of free [3H] steroid in the uterus was determined. Radioactive material was detected in all of the subcellular fractions of the uterus and identified as estradlol-17β. Similar subcellular distribution of the radioactivity was observed when [3H]E2-BSA was added to uterine homogenate. Free estradlo1-17β was released when the conjugate was Incubated with rat uterine homogenate or with serum. The results of the present study suggest that E2-BSA is hydrolyzed and under conditions. It is recommended that the stability of a hormone-protein conjugate be established before use. 相似文献
14.
Tetsuo Sawai Laura J. Crane J.O. Lampen 《Biochemical and biophysical research communications》1973,53(2):523-530
The plasma membrane-bound penicillinase of has been purified. Amino acid analysis showed no significant differences in composition between the enzyme and exopenicillinase. Enzyme purified from cultures containing H333PO4 or [3H]-glycerol contained 33P or [3H]-glycerol activity and treatment with 8 M urea, 0.2% sodium dodecyl sulfate at 80° C did not remove the 3H-activity from the enzyme protein. Trypsin readily cleaved the glycerol-containing moiety from the enzyme protein, forming enzyme with molecular weight and heat stability like that of the exoenzyme. Phospholipase D and C also produced enzyme resembling the exo-form. 相似文献
15.
The biosynthesis of 2-methylalkanes was studied in the crickets and . Labelled acetate, valine, and isobutyric acid were incorporated into the cuticular hydrocarbon of at levels of 6.0 ± 1, 6.5 ± 2, and 1.5 ± 0.7 percent respectively. The hydrocarbons of this insect are 20 percent 2-methylalkanes, primarily of even numbered carbon chain lengths, and 80% n-alkanes. Of the label incorporated into the hydrocarbon fraction, 28 ± 2 percent of sodium [1-14C] acetate, 98 ± 1 percent of L-[G-3H] valine, and 75 ± 10 percent of [1-14C] isobutyric acid were incorporated into the 2-methylalkanes. This suggests that valine is converted to isobutyric acid and is incorporated into the even numbered carbon chain length 2-methylalkanes during the initial stages of chain elongation. Similar data obtained in suggests that leucine is converted to isovaleric acid which is then incorporated into the odd numbered carbon chain length 2-methylalkanes. 相似文献
16.
Abdallah Ghalayini Robert E. Anderson 《Biochemical and biophysical research communications》1984,124(2):503-506
Isolated frog () retinas were labeled in the dark with either [32P]PO4-orthophosphate or -[2-3H]inositol for 2.5–4 hrs. After washing the retinas with cold buffer, they were exposed to brief flashes of light (5 secs or 15 secs) and their rod outer segments isolated. Upon separation of labeled phospholipids, a specific decrease in label in phosphatidylinositol 4,5-bisphosphate was observed, whereas there was no significant effect on the labeling of phosphatidylinositol 4-phosphate, phosphatidylinositol, or phosphatidic acid. These results are indicative of a light-activated phosphatidylinositol 4,5-bisphosphate-specific phospholipase C in frog rod outer segments. 相似文献
17.
M A Lea R Barra M R Koch H Hicks C Daly 《Biochemical and biophysical research communications》1977,75(2):519-524
L-1-tosylamido-2-phenylethyl chloromethyl ketone was observed to inhibit the incorporation of [3H] amino acids into protein and [3H] thymidine incorporation into DNA in Novikoff hepatoma ascites cells Similar effects were seen with several Morris hepatomas and a transplanted colon tumor in rats, and were accompanied by decreased uptake of isotope into acid soluble tissue fractions. Under the same conditions, there was no significant inhibition in regenerating liver and there was an increased uptake of [3H] amino acids in the livers of normal and tumor bearing rats. 相似文献
18.
Akiko H. Kumagai Nobu Akamatsu 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,499(3):447-449
Biosynthesis of moiety of streptomycin from d-glucose by Streptomyces griseus was studied. A mixture of d-[1-14C]glucose and d-[6-3H]glucose was given to the culture of S. griseus. The 3H/14C ratio found in further supports a mechanism that the conversion of d-glucose to l-hexose is carried out without scission of carbon skeleton. When d-[1-14C]glucose and d-[3-3H]glucose were used, the fall of 3H/14C ratio in showed that the hydrogen atom at C-3 plays a rôle in such a transformation. 相似文献
19.
David B. Fenske Robert J. Cushley 《Biochemical and biophysical research communications》1984,121(3):871-877
[2H]Chondroitin sulfate was prepared by partial -deacetylation of chondroitin sulfate ( hydrazinolysis) followed by treatment with [2H6]acetic anhydride. 2H NMR spectra of [2H]chondroitin sulfate in the presence of human plasma low density lipoprotein provide evidence for a soluble complex stoichiometry of 3 (and possibly 2) lipoproteins per polysaccharide molecule, and allow a rough estimation of the dissociation constant Kd. 相似文献
20.
Adriamycin inactivates cytochrome c oxidase by exclusion of the enzyme from its cardiolipin essential environment 总被引:3,自引:0,他引:3
E Goormaghtigh R Brasseur J M Ruysschaert 《Biochemical and biophysical research communications》1982,104(1):314-320
The regulation of ligand binding to the muscarinic acetylcholine receptor in developing chick heart has been studied using the radiolabeled antagonist [3H]quinuclidinyl benzilate (QNB). In assays containing only buffer and a source of receptor protein, the antagonist radioligand bound to a single, high affinity state of the receptor. If Mg2+ and EDTA were added, [3H]QNB bound to a single, low affinity state. The guanine nucleotide analog, guanylylimidodiphosphate [Gpp(NH)p], reversed the effect of so that [3H]QNB again bound only to a single, high affinity state. Sodium could also reverse the effect of on antagonist binding but the effects of sodium and Gpp(NH)p on [3H]QNB binding were not additive. 相似文献