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1.
Influence of protease inhibitors and energy metabolism on intracellular protein breakdown in starving Escherichia coli 总被引:6,自引:0,他引:6
Y Shechter D Rafaeli-Eshkol A Hershko 《Biochemical and biophysical research communications》1973,54(4):1518-1524
It has been reported that certain inhibitors of serine proteases block intracellular protein breakdown in subjected to nutritional deprivation. We show here that the protease inhibitors p-toluene sulfonyl fluoride and pentamidine isethionate inhibit protein breakdown in deprived of glucose, but not in bacteria starved for inorganic phosphate or ammonia. Furthermore, we find that the protease inhibitors cause a drastic decline in cellular ATP levels when glucose is omitted from the incubation medium. It is concluded that these protease inhibitors influence protein breakdown by interfering with cellular energy production, rather than by interacting with a specific serine protease. 相似文献
2.
Cultured epithelial monolayers of MDCK cells grown upon Millipore filter supports and mounted in Ussing chambers for transport studies respond to addition of adrenalin from only the basal bathing solution by an increased short-circuit current, due both to an increased transmonolayer potential difference (basal solution electropositive) and an increased transmonolayer conductance. Measurement of tracer Na+, K+ and Cl? fluxes demonstrate that the adrenalin-stimulated short-circuit current results primarily from basal to apical net Cl? secretion. Half-maximal stimulation of the short-circuit current was observed at (; the order of potency of adrenergic agonists for short-circuit current stimulation was , consistent with adrenalin action being mediated by a β-adrenergic receptor. The adrenalin-stimulated short-circuit current was sensitive to inhibition (75%) by basal additions of furosemide (); phloretin inhibition (54%, 57%) was observed from both epithelial surfaces. Amiloride (10?4 M) and 4-acetamido-4-isothiocyanostilbene-2, 2′-disulphonic acid (SITS) (10 μM) were ineffective as inhibitors of the adrenalin response. The increased short-circuit current was sensitive to replacement of medium Na+ by choline (87%) and Tris (93%). Li+ was a partially effective substitute cation for Na+ · NO3?, and isethionate were ineffective substitutes for Cl? whereas Br? was partially effective. Partial replacement of medium Na+ by choline gave an upward-curving non-saturable dependence of the adrenalin-stimulated short-circuit current upon [Na]; partial replacement of Cl? by NO3? in contrast gave a saturable increase with a of approx. 65 mM Cl?. 相似文献
3.
The effects of 19-hydroxy-prostaglandins (19-OH-PGs) were tested on the rabbit oviduct and uterus and on the rhesus monkey () uterus. The 19-OH-PGEs suppressed spontaneous oviductal and uterine activity in the rabbit. The qualitative effect on the rabbit oviduct of 19-OH-PGEs was similar to that of PGE2. However, the typical response of the rabbit uterus to PGE2 was an increase in muscle activity. With regard to the rabbit oviduct, 19(R)-OH-PGE2 was as potent as PGE2, but 19(S)-OH-PGE2 was approximately as potent as PGE2. Based on the dose of 19-OH-PGEs usually required to cause a minimal suppression and the dose of PGE2 required to cause a minimal stimulation of rabbit uterine activity, 19(R)-OH-PGE2 was twice as potent as PGE2 while 19(S)-OH-PGE2 was as potent as PGE2. Stimulatory effects on the rabbit oviduct and uterus were observed following administration of 19-OH-PGEs and PGF2α. The potency on the rabbit oviduct of 19(S)-OH-PGF2α was about to that of PGF2α; the potency of 19(R)-OH-PGF2α was about to that of PGF2α. Both 19-OH-PGFs were approximately to as potent as PGF2α on the rabbit uterus. At the doses tested 19-OH-PGFs were inactive on the monkey uterus. Thus, these compounds are at least as active as PGF2α. In contrast, 19(R)-OH-PGE2 had approximately the same potency as PGE2 in stimulating monkey uterine activity; but 19(S)-OH-PGE2 was approximately as potent as PGE2. 相似文献
4.
Day 7 to 9 embryos were frozen by a rapid two-step method to ?38°C before being plunged into liquid nitrogen. Glycerol was used as the cryoprotectant and, following thawing, the embryos were cultured for 12 – 24 hours in PBS + 15% heat-treated steer serum. In Experiment 1, embryos were frozen in 2.0 ml glass ampoules or 0.5 ml Cassou straws. Two levels of glycerol (1.0M and 1.4M) gave comparable survival rates ( and , respectively). A greater proportion of embryos developed in culture after freezing in straws. In Experiment 2, embryos were classified morphologically before and after freezing into 5 grades (1 = excellent; 2 = good; 3 = fair; 4 = poor; 5 = degenerate). Only embryos of grade 1, 2 and 3 were frozen. The post-thaw survival rates for embryos graded 1, 2 and 3 before freezing were 100% (), 86% () and 83% (), respectively. Furthermore, the porportion of surviving embryos estimated to be of poor quality (grade 4) was greater for embryos graded 3 before freezing () than for embryos graded 2 () or 1 (). The percentage of embryos which developed normally after culture for each of the pre-freezing grades 1, 2 and 3 was 91% (), 50% () and 29% (), respectively. Of the total number of frozen-thawed embryos which developed in culture, (16%) were of poor quality. The proportion of poor quality developing embryos was greater inembryos graded 3 before freezing () than those graded 2 (). All of the embryos graded 1 before freezing and which developed in culture were of good quality. Results indicate that, if high post-thaw survival rates are to be obtained, stringent embryo selection processes will be required. 相似文献
5.
OKY-1581 is an effective inhibitor of thromboxane synthesis and . The generation of thromboxane B2 (TxB2), prostaglandin E (PGE) and prostaglandin F (PGF) was measured following clotting and during platelet aggregation induced by collagen. The presence of OKY 1581 either or caused a reduction in TxB2 generation during clotting and platelet aggregation with a concomitant increase in PGE and PGF. The effect could be observed two hours after oral or subcutaneous administration of 5 to 100 mg per rabbit and lasted for 24 to 48 hours. The reduction in TxB2 was not accompanied by an inhibition of clotting or platelet aggregation. OKY-1581 appears to be a suitable agent for studying the role of TxB2 in atherosclerosis. 相似文献
6.
Jean Grandjean Pierre Laszlo 《Biochemical and biophysical research communications》1982,104(4):1293-1297
Transport of Pr3+ across phosphatidylcholine vesicles, monitored through 31P nmr, is first-order in monensin (), second-order in etheromycin () or in lasalocid A (). When and (or and ) are incorporated in 1:1 ratio into the lipidic phase, transport is faster than with each ionophore alone. For instance, assuming that the complexes .Pr3+., .Pr3+., and .Pr3+ are equiprobable, they effect transport at intrinsic relative rates of 1, 2, and 13.5, a remarkable synergism is set up. 相似文献
7.
2-Acetamido-2-deoxy-3-O-(D-2-propionyl-L-alanine)-D-glucopyranose () and 2-acetamido-2-deoxy-3-O-(D-2-propionyl-L-alanyl-D-isoglutamine)-D-glucopyranose () have been synthesized by condensation of benzyl 2-acetamido-4,6-O-benzylidene-3-O-(D-1-carboxyethyl)-2-deoxy-β-D-glucopyranoside () respectively with the L-alanine derivative and the dipeptide , followed by debenzylidenation and hydrogenolysis. Compound is adjuvant active, whereas is inactive, so that is the smallest adjuvant active structure for the time being. 相似文献
8.
The Dieckmann condensation of dimethyl 3, 4--5α-cholestan-3, 4-dioate (), using sodium methoxide in benzene under reflux for two hours, is shown to give 2α-carbomethoxy-A-nor-5α-cholestan-3-one (). Confirmation of the stereochemistry of the β-keto ester was obtained through its sodium borohydride reduction product, 2α-carbomethoxy-A-nor-5α-cholestan-3β-ol (). 相似文献
9.
Penile intromissions have been thought to be the primary stimulus for reflex ovulation in light-induced persistent estrus (LLPE) rats, even though other stimuli also trigger reflex ovulation. To clarify the nature of these noncoital stimuli, intact (nonadrenalectomized) LLPE rats were briefly exposed to a variety of environmental stimuli, other than intromissions, and checked for ova 19–22 hr later. Summary of results (number of rats ovulating/number of rats tested): (A1) home cage (); (B1) home cage + vaginal taping (); (C1) home cage + male-soiled bedding (); (D1) novel cage (); (E1) novel cage + vaginal taping (); (F1) novel cage + vaginal taping + male-soiled bedding (); (G1) novel cage + vaginal taping + male-soiled bedding + male mounts without intromissions (). The percentage of LLPE rats that ovulated in the last-mentioned test condition was related to the degree of proceptivity/receptivity of the LLPE females. Eight of eight proceptive LLPE females ovulated, but only nonproceptive females ovulated. To account for reflex ovulation in the absence of intromission it has been suggested that adrenal progesterone (P) stimulates release of an ovulatory quota of luteinizing hormone. This study demonstrates no significant differences in percentage of LLPE females ovulating in corresponding groups of adrenalectomized (ADX) and adrenal-intact females. Summary of results: A2 = , B2 = , C2 = , D2 = , E2 = , F2 = , G2 = . Conclusion: (a) Exposure to a factor in male-soiled bedding induces reflex ovulation in a significant proportion of adrenal-intact LLPE animals while exposure to a novel cage and/or vaginal taping does not, (b) penile intromissions are not the primary stimulus for reflex ovulation in intact proceptive LLPE rats, and (c) adrenal P is not required for reflex ovulation after tests with noncoital stimuli. 相似文献
10.
A series of analogues of dopamine (DA) with varying degrees of conformational flexibility have been examined as potential substrates or competitive inhibitors of the enzyme norepinephrine N-methyltransferase (NMT). A conformationally defined (rigid) analogue of the fully extended conformation of DA, 2-amino-6, 7-dihydroxybenzonorbornene hydrobromide (; 6, 7-D2HX) proved to be a better substrate than the non-catechol parent 2-aminobenzonorbornene (; 2HX). However, analogues and displayed equivalent competitive inhibitory activity toward phenylethanolamine (PEA). Neither 6, 7-ADTN (5), a DA analogue in the 2-aminotetralin (2AT) system, nor 6, 7-DTHIQ (), a DA analogue in the tetrahydroisoquinoline (THIQ) system, showed substrate activity; 6, 7-ADTN was a poorer competitive inhibitor than the parent 2AT but 6, 7-DTHIQ was a better competitive inhibitor than its parent, THIQ (). A tricyclic conformationally defined analogue of 6, 7-ADTN was devoid of either substrate or inhibitory activity. From these results it may be concluded that a fully extended side chain conformation is required for NMT substrate activity, and the better substrate activity for 6, 7-D2HX compared to is consistent with a proper catechol orientation for interaction with the norepinephrine (NE) binding site of NMT. 相似文献
11.
Theodore Dashman 《Life sciences》1980,27(15):1415-1422
The enol-ether amino acid, L-2-amino-4-methoxy--butenoic acid (AMTB) is an inhibitor of porphobilinogen synthase (PBG synthase) when added prior to the addition of the substrate δ-aminolevulinic acid. The inhibition of PBG synthase by several stereoisomers and analogues of AMTB was investigated to determine those structural features of AMTB which may be necessary for inhibition. The D- isomer was also an inhibitor after preincubation, whereas the L- isomer inhibited with or without preincubation. The amino acid analogues, DL-vinylglycine, DL-2-aminobutanoic acid, the reduced form of L-2-amino-4-methoxy--3-butenoic acid, L-2-amino-4-(2-aminoethoxy)--3-butenoic acid and its reduced congener did not inhibit PBG synthase even with preincubation. This structure activity relationship indicates that the double bond and methoxy moiety of L-2-amino-4-methoxy--3-butenoic acid are probably required for inhibition.Heme, when preincubated with PBG synthase, was an inactivator of the enzyme. However, when both L-2-amino-4-methoxy--3-butenoic acid and heme were simulatneously preincubated with PBG synthase, inactivation of the enzyme was greater than with either compound separately. The possibility of multiple catalytic sites was suggested by the use of multiple inhibition kinetics in the presence of heme and L-2-amino-4-methoxy--3-butenoic acid. 相似文献
12.
Six ovariectomized mature cows each of Brahman (B), Brahman × Hereford (BH) or Hereford (H) breeding were injected intramuscularly with Estradiol-17β (E). Dose levels of 1, 2, 4 and 8 mg E were given in 2 ml corn oil. Cows were allowed a 2 week recovery period between treatments. After injection the cows were placed with 18 epididymectomized bulls and observed constantly for 36 hours. B failed to accept the bulls at any E dose level. Proportions of BH accepting the bull were , , and and proportions of H accepting the bull were , , and at 1, 2, 4 and 8 mg E, respectively. BH were less responsive at 1 mg E than H (P<.10) and B were less responsive at any level (P<.005). The number of stances increased significantly with dose level (P<.005) and a breed × dose level interaction (P<.10) was found. The duration of standing estrus behavior was longer in H cows at 1 and 2 mg E than in BH (P<.05) but was identical at 4 and 8 mg E. Duration of estrus was shorter in B except at the 2 mg dose level. Breed (P<.005) and breed × dose level interactions (P<.05) were found. Response time (injection of E to stance event) did not differ between dosages of E within breed groups. However, response time was significantly longer in B (19.3 hrs, P<.05) versus the response time of either H (10.1 hrs) or BH (12.8 hrs). If homosexual stance behavior is accepted as estrus, B were less responsive at 1, 2, 4 and 8 mg E than were BH or H (P<.10). 相似文献
13.
Luis O. Rodriguez Sidney M. Hecht 《Biochemical and biophysical research communications》1982,104(4):1470-1476
Consistent with a recent literature report (Repine, J. E. (1981) , 1001–1003), the release of [3H]-thymine from PM-2 DNA by Fe(II)-H2O2-generated ·OH was suppressed by dimethyl sulfoxide. In contrast, DMSO did not affect [3H]-thymine release mediated by Fe(II)-bleomycin. Under aerobic conditions in the presence of -butyl phenylnitrone, Fe(II)-BLM produces an epr signal that has been presumed to arise by transfer of ·OH or from the “active complex” of bleomycin to the spin trap. Remarkably, high concentrations (80 mM) of PBN had no effect on the ability of Fe(II)-BLM to solubilize [3H]-thymine, although the ability of authentic ·OH to degrade DNA was completely suppressed under these condition. The suproxide dismutase catalyst tetrakis(4-N-methylpyridyl)porphineiron(III) also failed to suppress BLM-mediated DNA degradation. Moreover, the epr signal observed with 1.6 mM Fe(II)-BLM in the presence of 80 mM PBN was found to be much less intense than that produced by 1.6 mM Fe(II) and 290 mM H2O2, but equivalent in intensity to that obtained with 45 mM Fe(II) and exoess H2O2. We conclude that the fragmentation of DNA produced by Fe(II)-BLM can be due neither to free ·OH nor to . We suggest that DNA degradation is initiated by an “active complex” consisting of BLM, metal and oxygen that functions by abstracting H· from susceptible sites on DNA. 相似文献
14.
Uterine stage embryos collected from the hamster (8-cell) and cow (morula, early blastocyst) were monitored for development (embryo culture) and (embryo transfer) following premature removal of the zona pellucida.Removal of the zona pellucida did not significantly affect development to the blastocyst stage of (1) 8-cell hamster embryos (zonae removed by a combined enzymic-mechanical procedure), (2) bovine morulae (zonae removed by mechanical means only) (3) early bovine blastocysts (zonae removed by the enzymic-mechanical technique).Zona-free hamster embryos formed significantly fewer viable fetuses than did zona-intact embryos. The lower incidence of fetal development observed following transfer of zona-free 8-cell hamster embryos may have resulted in part from the formation of chimeras by fusion of these embryos . Such fusion was observed to occur between zona-free embryos placed in close proximity. The proportion of pregnancies resulting from transfer of bovine blastocysts cultured from zona-free morulae was similar to that of zona-intact embryos.In this study we have demonstrated that (1) enzymic and mechanical procedures used to remove zonae pellucidae from uterine-stage hamster and bovine embryos do not adversely affect subsequent development of these embryos and and (2) zonae pellucidae are not required for normal development of these embryos. These findings have implications for microsurgery of mammalian embryos and for embryo transfer. 相似文献
15.
W.A. Deutsch A.L. Spiering G.R. Newkome 《Biochemical and biophysical research communications》1980,97(3):1220-1226
The -isomer of the antitumor drug dichlorodiammineplatinum(II) [-Pt(II)] was tested for its abilty to introduce nicks (single-strand breaks) into supercoiled PM2 DNA. Whereas incubations up to 24 h show no indication of -Pt(II)-treated DNA having single-strand breaks, DNA interstrand cross-links were detected in the first 15 min of incubation. Furthermore, the formation of DNA interstrand cross-links was inhibited and fully reversed after incubation with 2 mM thiourea. 相似文献
16.
Cellular aspects of tolerance. VII. Inheritance of the resistance to tolerance induction 总被引:1,自引:0,他引:1
The half-lives of elimination () of 131I-RGG from the body of normal A or Balb/c animals was much longer than the of SJL mice. At all ages, the of normal hybrids (A × SJL, SJL × A, Balb/c × SJL) was similar to or longer than that of the A or Balb/c parents. Thus, in terms of the of normal animals, the SJL responsiveness to 131I-RGG appeared to be a recessive trait. Tolerance could be induced in newborn animals and, in terms of , the degree of unresponsiveness at the age of 6 weeks, was the same in A, Balb/c, A × SJL, and Balb/c × SJL animals but was much shorter in SJL mice. Thus, in neonatally induced tolerance, the duration of tolerance was recessive for the SJL type. The average after tolerance induction in 3-week-old hybrids (A × SJL, SJL × A, Balb/c × SJL) was similar to that of the A or Balb/c parent, but by the 8th and 12th week it approached the average of the SJL parent. Comparing 8-week-old hybrids, the average was longest in A × SJL hybrids and identical in SJL × A and Balb/c × SJL mice. An examination of distribution in various 8- and 12-week-old crosses and backcrosses revealed a fairly large proportion of individuals with a which was intermediate between SJL and the other parent. There was a tendency for this number to decrease in 12 weeks as compared to 8-week-old mice. In 8-week-old mice, the number of animals with intermediate was smallest when SJL was the maternal animal [(SJL × A); SJL × (A × SJL); SJL × (SJL × A)]. There was no link between of tolerant animals and either the immunoglobulin allotype (MuAl/MuA2) or the C5 eniotype (MuB1 positive/MuB1 negative). 相似文献
17.
A series of 12α-hydroxy steroids with varying side chains was prepared, and their 24-hour acetylation yields were compared, l2α-Hydroxy-5β-pregnan-20-one () was prepared from 3α, 12α-diacetoxy-5β~pregnan-20-one () and also by side chain degradation of 12α-acetoxy-5β-cholanoic acid (). 21-Benzyl-5β-pregnan-12α-ol () was synthesized by hydrogenation of the 21-benzylidine derivative of ketone . 23-Pheny1-5β-norcholan-12α-ol () was obtained by the Grignard reaction of 2-phenyl-ethylmagnesium bromide and ketone , dehydration, hydrogenation and hydride reduction; a similar sequence produced 20-methyl-5β-pregnan-12α-ol (). The acetylation results (Table 11) imply that branching at C-20 may be more significant for 12α-hydroxyl reactivity than side chain length or type. An additional compound with an unbranched side chain, 21-nor-5β-cholan-12α-ol (), was synthesized by a Grignard reaction on the 21-bromo intermediate . Acetylation rates determined by glc indicate (Table 111) That compounds with unbranched side chains have 12α-hydroxyl groups about ten times as reactive as their analogs with 20-methyl groups. 相似文献
18.
Robert L. Wykle Craig H. Miller Jon C. Lewis Jeffrey D. Schmitt Jennie A. Smith Jefferson R. Surles Claude Piantadosi Joseph T. OFlaherty 《Biochemical and biophysical research communications》1981,100(4):1651-1658
1-O-Hexadecyl-2-O-acetyl--glycero-3-phosphocholine (platelet activating factor) stimulated the degranulation of rabbit platelets and human neutrophils, whereas the enantiomer, 3-O-hexadecyl-2-O-acetyl--glycero-1-phosphocholine, was inactive. The analogs compared had the following relative potencies in degranulating platelets and neutrophils: 1-O-hexadecyl-2-O-acetyl--glycero-3-phosphocholine > 1-O-hexadecyl-2-O-ethyl--glycero-3-phosphocholine >-1-O-octadecyl-2-O-ethylglycero-3-phosphocholine = 1-O-hexadecyl-2-O-methyl--glycero-3-phosphocholine >-1-O-dodecyl-2-O-ethyl-glycero-3-phosphocholine. The deacetylated compound, 1-O-hexadecyl-2-lyso--glycero-3-phosphocholine, and 1-O-hexadecyl-2,2-dimethylpropanediol-3-phosphocholine were inactive. The active analogs selectively desensitized the response to each other in the neutrophils. It is suggested that these compounds may activate cells through interaction with a stereospecific receptor. 相似文献
19.
Yoichi Taya Susumu Nishimura 《Biochemical and biophysical research communications》1973,51(4):1062-1068
A new enzyme, which catalyzes the transfer of a methyl group to tRNA to form 5-methylaminomethyl-2-thiouridylate, was isolated from by a procedure including affinity chromatography. The purified enzyme was nearly homogeneous upon disc electrophoresis. Using methyl-deficient tRNAGlu of as substrate, the 5-methylaminomethyl-2-thiouridylate residue synthesized was mostly found in the anticodon loop, showing a coincidence of the modification site with that . 相似文献
20.
Controlled alkaline hydrolysis of 16α-bromo-17-keto steroids , and with potassium carbonate and tetra-n-butylammonium hydroxide (n-Bu4NOH) and synthesis of 2α-hydroxy-3-ones , and by the controlled hydrolysis of the corresponding 2α-bromo-3-ones , and are described. Treatm carbonate in aqueous acetone or with n-Bu4NOH in aqueous dimethylformamide (DMF) gave 16α-hydroxy-17-ones , and in 85–90% yield, respectively. 2α-Hydroxy-3-ones , and were obtained by hydrolysis of the corresponding bromoketones , and in high yields using the above conditions or sodium hydroxide in pyridine or DMF, respectively. Deuterium labeling experiments suggested that equilibration between the 2α-bromoketone and the 2β-bromo isomer precedes the formation of the ketol in which the true intermediate might be the 2β-isomer . However, rearranged androstane derivatives, 3β-hydroxy-2-ones and , were stereoselectively obtained by treatment of the bromoketones and with an excess amount of sodium hydroxide. 相似文献