首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
A glycoprotein from the stems and leaves of the Dolichosbiflorus plant that cross reacts with antibodies to the seed lectin has been found to bind to affinity columns of blood group A + H substance covalently linked to Sepharose. This binding of the cross reactive material to the affinity resin differs from that of the seed lectin in that it is easily dissociated with 0.15 M NaCl. Affinity electrophoresis using entrapped blood group A + H substance shows that the carbohydrate binding activity of the cross reactive material is weakly inhibited with N-acetyl-D
-galactosamine and N-acetyl-D
-glucosamine. Glucose, mannose and galactose gave no inhibition when tested at concentrations of 50 mM. These data indicate that the specificity of the cross reactive material is somewhat different from the N-acetyl-D
-galactosamine specificity of the seed lectin. The significance of these findings is discussed in relation to the structural similarities of the cross reactive material and the seed lectin.  相似文献   

2.
The plasma membrane-bound penicillinase of Bacilluslicheniformis749C 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   

3.
Extracts of 40 hr Artemiasalina nauplii can convert a heavy form of elongation factor 1 (EF-1H) to a light species (EF-1L). The data indicate that a protease in the extracts is responsible for this reaction, and these findings may explain the observation that extracts from Artemiasalina nauplii have only EF-1L whereas before hatching of the Artemiasalina embryos EF-1H is the predominant species (Slobin and M?ller [1975] Nature 258, 452–454).  相似文献   

4.
The synthesis and characterization of E- and Z-3,4-bis(4-hydroxyphenyl)-2-hexene (E- and Z-pseudo-DES) and of Z-3,4-bis(4-hydroxyphenyl)-2-hexen-1-ol (Z-1-hydroxypseudo-DES) are described. These compounds are useful as probes in the study of hormone action.  相似文献   

5.
Timothy G. Kingan 《Life sciences》1981,28(23):2585-2594
Standard biochemical procedures were used to purify the prothoracicotropic hormone (PTTH) 4400 fold from whole head extracts of Mandurasexta fifth instar larvae. Hormonal activity was bioassayed by injection into neck-ligated fourth instar larvae. The hormone was stable to heating at 85°C. Ammonium sulfate and acetone fractionation provided a crude preparation which showed dose-dependent activity in the bioassay. Chromatography on Sephadex G-100, DEAE-Sephadex, and hydroxylapatite gave a preparation with 2.6 Manduca PTTH units/μg protein (4400-fold purification). Activity was sensitive to proteolytic enzymes. Further purification by preparative electrophoresis gave a preparation which migrated as a single band in two polyacrylamide gel electrophoresis systems. A molecular weight estimate of 25,000 Daltons was obtained for this bands on SDS polyacrylamide gels.  相似文献   

6.
Guanylate cyclase from crude homogenates of vegetative Dictyosteliumdiscoideum has been characterized. It has a pH optimum of 8.0, temperature optimum of 25°C and requires 1 mM dithiothreitol for optimal activity. It strongly prefers Mn++ to Mg++ as divalent cation, requires Mn++ in excess of GTP for detectable activity, and is inhibited by high Mn++ concentrations. It has an apparent Km for GTP of approximately 517 μM at 1 mM excess Mn++.The specific activity of guanylate cyclase in vegetative homogenates is 50–80 pmoles cGMP formed/min/mg protein. Most of the vegetative activity is found in the supernatant of a 100,000 x g spin (S100). The enzyme is relatively unstable. It loses 40% of its activity after 3 hours storage on ice. Enzyme activity was measured from cells that had been shaken in phosphate buffer for various times. It was found that the specific activity changed little for at least 8 hours. Cyclic AMP at 10?4 M did not affect the guanylate cyclase activity from crude homogenates of vegetative or 6 hour phosphate-shaken cells.  相似文献   

7.
The transducing phage λdarg14, carrying a portion of the E. coli chromosome including argECBH, is derived from the heat-inducible, lysis-defective strain λy199, which has the b519 and b515 deletions. Cleavage of λy199 DNA by EcoRI endonuclease, followed by agarose slab gel electrophoresis, results in bands corresponding to the known C, D, E, and F segments of λ, and a segment A′ (A plus B minus b519 minus b515, the cleavage site between A and B being eliminated). Cleavage of λdarg14 DNA by EcoRI yields the expected D, E, and F segments of λ and four other segments, termed 14-1 through 14-4, whose length is 17.5, 6.2, 3.0, and 2.0 kilobases, respectively, as determined by electron microscopy and corroborated by electrophoretic mobility. Heteroduplex analysis shows that the E. coli argECBH cluster is on the 14-1 segment.  相似文献   

8.
OKY-1581 is an effective inhibitor of thromboxane synthesis invivo and invitro. 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 invivo or invitro 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   

9.
The thermally-induced changes of a cytochrome P-450 dependent activity (ethoxycoumarin-O-deethylase) and of the fluorescence polarization of diphenylhexatriene were compared in microsomes from lean, obob and dbdb mice. In lean mice, biphasic plots were obtained with break points in the same range of temperature by both methods, whereas, in obob and dbdb mice, no discontinuities were observed. These results may be related to a modified fatty acid composition of microsomal membranes in mutant mice. They exemplify the influence of the lipid environment on the monooxygenase system as also shown by the modified binding constants of cytochrome P-450 towards type II substrates in dbdb mice.  相似文献   

10.
An inhibitor of Streptococcus,mutans endodextranase was detected in proteins prepared from batch cultures of S.,mutans strains representing serotypes a through g. Affinity chromatography of strain 6715-49 proteins, which apparently were free of endodextranase activity, yielded an active endodextranase and, in a separate peak, the endodextranase inhibitor. The presence of the inhibitor in culture fluids accounts for the absence of endodextranase activity in batch-grown cultures of S.,mutans known to produce this enzyme.  相似文献   

11.
Uterine stage embryos collected from the hamster (8-cell) and cow (morula, early blastocyst) were monitored for development invitro (embryo culture) and invivo (embryo transfer) following premature removal of the zona pellucida.Removal of the zona pellucida did not significantly affect invitro 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 inutero. Such fusion was observed to occur invitro 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 invitro and invivo 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   

12.
With muscle glycogen phosphorylase a and b, 5-thio-D-glucose is a non-competitive inhibitor toward phosphate where it has a Ki of 13 mM and 5.1 mM, respectively, and produces a mixed type of inhibition when glycogen is the substrate.5-Thio-D-glucose enhances diaphragm phosphorylase phosphatase activity to the same extent as D-glucose, yet the thioanalog does not affect phosphorylase b kinase. Thus, the action of 5-thio-D-glucose on glycogen degradation proceeds by inhibition of phosphorylase a and b and by inactivation of phosphorylase a through converting it to the b form.  相似文献   

13.
Both pairs of dl-ll-desoxy- and dl-13-cis-erythro-15, 16-dihydroxyprostaglandins have been synthesized via 1,4-conjugate additions of an appropriately functionalized cis-vinyl cuprate to the requisite cyclopentenone. These prostaglandin analogs are considerably less potent than PGE2 as gastric secretion inhibitors or as bronchodilators.  相似文献   

14.
The quantity of organic acids ( lactic acid, acetic acid, propionic acid and butyric acid ) in the content of the gastrointestinal tract of germ-free and conventional rats and the invitro effects of the organic acid on the motility of the gastrointestinal tract of rats were investigated.Organic acids were detected only in the gastrointestinal contents of conventional rats but not in those of germ-free rats.Lactic acid detected in the stomach of rats stimulated the motility of both small and large bowel while acetic acid, propionic acid and butyric acid found in the cecum stimulated the motility of the large bowel but not of small bowel.  相似文献   

15.
Strain S296, isolated by screening 2000 colonies after nitrosoguanidine mutagenesis, yields extracts with less than 1% of wild-type RNase activity against (3H) poly(U). Unlike other E.coli strains, S296 grows with a doubling time of about 2 hr., both in nutrient broth and in minimal medium, and at 30°, 37° and 42°. The strain retains 10 to 20% of wild-type exonuclease activity against (3H) rRNA or T4 phage-specific mRNA; but two further mutants, made by screening mutagenized colonies of strain S296, are reduced to 3% of wild-type activity against those substrates as well.  相似文献   

16.
Rabbit anti-fluorescyl antibody producing lymphoid cells incubated invitro with LSD do not secrete the 7S form of immunoglobulin. The low molecular weight extracellular labeled material shows no measurable anti-fluorescyl antibody activity. Results indicate that during a short incubation period LSD interferes with tryptophan incorporation into antibody protein.  相似文献   

17.
A mutant strain (PL pT 1143) of Pseudomonasputida PL, has been isolated for its inability to growth with p-cymene as carbon source. The mutant oxidizes p-cymene (and p-cumate) to a compound (λmax 293 nm) which is readily converted to 3-hydroxy-p-cumate by acid. 4-Trifluoromethylbenzoate is oxidized by the mutant to an acid-stable intermediate (λmax 277nm) that has been crystallized. The spectral properties (u.v., i.r., NMR and mass) of this metabolite are consistent with those expected for a 2,3-dihydro-2,3-dihydroxy derivative of 4-trifluoromethylbenzoate. Further support of this structure was provided by elemental analysis and the properties of two derivatives of the metabolite, 4-trifluoromethyl-3-hydroxybenzoate and an acetonide formed with 2,2-dimethoxypropane. The stability of a product obtained by treatment of the dihydrodiol metabolite with triacetylosmate indicates that it is the cis-isomer.  相似文献   

18.
The paromomycin producing organism Streptomycesrimosusforma paromomycinus is resistant to this antibiotic and contains a phosphotransferase which inactivates paromomycin. The gene encoding this enzyme has been inserted in the Streptomyces vector pIJ702 and then cloned in Streptomyceslividans, selecting for paromomycin-resistance. Three plasmids have been isolated and one of them, pMJ1, contains a 2.2 kb insert with a single HindIII restriction site. Insertion of foreign DNA in this site blocks the expression of the phosphotransferase enzyme indicating that it is within the cloned gene. These findings provide a new dominant selective marker for Streptomyces cloning vectors with the versatility of insertional inactivation.  相似文献   

19.
Rhodotorucine A which induces mating tube formation of a cells in Rhodosporidiumtoruloides is metabolized rapidly by a cells. By use of labeled rhodotorucine A, the degradation was found to be proteolytic. Two peptide fragments Tyr-Pro-Glu-Ile-Ser-Trp-Thr-Arg and Asn-Gly-Cys(S-farnesyl) were identified as the metabolites. Proteolysis of the pheromone mainly occurred on the cell surface. Culture filtrate of a cells at log phase did not metabolize rhodotorucine A.  相似文献   

20.
This case report addresses the occurrence of Brucellosis and its effect on the cattle in developing countries. Three Zebu bulls (Bosindicus) are presented and the clinical and pathologic signs are described. Conception rates declined following an abortion storm in one herd and without prior abortions in another herd. Semen collected by electro-ejaculation was found to be azoospermic or with very few spermatozoa. B. abortus was isolated from seminal vesicles, testes and epididymides. Organs affected and showing microscopic lesions were testes, epididymides and seminal vesicles. The latter were not consistently affected. None of the bulls showed impairment of libido or breeding capacity.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号