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991.
Summary The administration of progesterone to ovariectomized rats induces an increase in the volume density (Vv) of the mitochondria and the appearance of giant mitochondria in the uterine glandular cells. This experimental model, including a stereological analysis, allowed us to investigate and quantify a direct effect of progesterone on a well-defined cellular structure without the intervention of estrogen in a priming phase. Synthetic compounds, promegestone, gestrinone and RU 38486, were tested in this model either in place of progesterone or simultaneously with progesterone. The potent progestomimetic activity of promegestone was confirmed by the proliferation of giant mitochondria and a high Vv value for the mitochondria, the two other compounds being inactive even at higher doses. At lower doses, gestrinone and RU 38486 partially inhibit the action of progesterone and at higher doses they both show a complete antagonist effect by preventing the development of the mitochondria. 相似文献
992.
An indirect enzyme-linked immunoadsorption assay (ELISA) was developed for cytochrome c3 using antisera to the cytochromes fromDesulfovibrio africanus Benghazi, Desulfovibrio vulgaris Hildenborough andDesulfovibrio salexigens British Guiana. The ELISA system was used to test for cross-reactions between these antisera and the heterologous antigens. In contrast to previous experiments using the Ouchterlony technique, all of the cytochromes c3 tested exhibited some degree of cross-reaction. Considerable variation was seen in cross-reactions for cytochromes c3 from differing strains ofD. desulfuricans. This observation raises questions about the taxonomic relatedness of these strains. No cross-reaction was seen with eukaryotic cytochrome c or withD. vulgaris cytochrome c553. The data demonstrate that cytochrome c3 is capable of undergoing nonprecipitating cross-reactions, and thus may not be as immunologically unique as was once thought.Abbreviations ELISA
Enzyme-linked immunoadsorption assay 相似文献
993.
994.
Paul Kuppert Siegrun Wilhelm Klaus-Dieter Spindler 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,128(2):95-100
Summary From in vitro experiments using different binding assays it is in crayfish demonstrated that the cytosol of target tissues is able to bind both ecdysone and ecdysterone. The ability to bind ecdysteroids is destroyed by heating and by treatment with -chymotrypsin and N-ethyl-maleinimide (NEM) (Figs. 4, 5). In target tissues there is a strong positive correlation between protein content and binding (Fig. 6). The association of the hormone-protein-complex is rapid, taking only a few min even at 5° C (Fig. 3). The binding of the two hormones to the cytosol is both specific and saturable. The association constants for the cytoplasmic receptors from hypodermis, hindgut and midgut gland are in the range of 3–6×107 M–1 for ecdysone and 5–7×108 M–1 for ecdysterone (Fig. 8). The data suggest the existence of cytoplasmic ecdysteroid receptors. 相似文献
995.
996.
Structure and enzymic activity of ribonuclease-A esterified at glutamic acid-49 and aspartic acid-53
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A. Seetharama Acharya Belur N. Manjula Paul J. Vithayathil 《The Biochemical journal》1978,173(3):821-830
The dimethyl ester of bovine pancreatic ribonuclease-A (dimethyl RNAase-A), the initial product of esterification of RNAase-A in anhydrous methanolic HCl, was isolated in a homogeneous form. The two carboxy functions esterified in this derivative are those of glutamic acid-49 and aspartic acid-53. There were no changes in the u.v.-absorption spectral characteristics, the accessibility of the methionine residues, the resistance of the protein to proteolysis by trypsin and the antigenic behaviour of RNAase-A as a result of the esterification of these two carboxy groups. Dimethyl RNAase-A exhibited only 65% of the specific activity of RNAase-A, but still had the same Km value for both RNA and 2′:3′-cyclic CMP. However, the Vmax. was decreased by about 35%. On careful hydrolysis of the methyl ester groups at pH9.5, dimethyl RNAase-A was converted back into RNAase-A. Limited proteolysis of dimethyl RNAase-A by subtilisin resulted in the formation of an active RNAase-S-type derivative, namely dimethyl RNAase-S, which was chromatographically distinct from dimethyl RNAase-A and had very nearly the same enzymic activity as dimethyl RNAase-A. Fractionation of dimethyl RNAase-S by trichloroacetic acid yielded dimethyl RNAase-S-protein and dimethyl RNAase-S-peptide, both of which were inactive by themselves but regenerated dimethyl RNAase-S when mixed together. Dimethyl RNAase-A-peptide was identical with RNAase-S-peptide. RNAase-S-protein could be generated from dimethyl RNAase-S-protein by careful hydrolysis of the methyl ester groups at pH9.5. The interaction of dimethyl RNAase-S-protein with RNAase-S-peptide appears to be about 4-fold weaker than that between the RNAase-S-protein and RNAase-S-peptide. Conceivably, the binding of the S-peptide `tail' of dimethyl RNAase-A with the remainder of the molecule is similarly weaker than that in RNAase-A, and this brings about subtle changes in the geometrical orientation of the active-site amino acid residues of these modified methyl ester derivatives. It is suggested that these changes could be responsible for the generation of the catalytically less-efficient RNAase-A and RNAase-S molecules (dimethyl RNAase-A and dimethyl RNAase-S respectively). 相似文献
997.
RNA synthesis during morphogenesis of the fungusMucor racemosus 总被引:6,自引:0,他引:6
Bacteroides succinogenes produces acetate and succinate as major products of carbohydrate fermentation. An investigation of the enzymes involved indicated that pyruvate is oxidized by a flavin-dependent pyruvate cleavage enzyme to acetyl-CoA and CO2. Active CO2 exchange is associated with the pyruvate oxidation system. Reduction of flavin nucleotides is CoASH-dependent and does not require ferredoxin. Acetyl-CoA is further metabolized via acetyl phosphate to acetate and ATP. Reduced flavin nucleotide is used to reduce fumarate to succinate by a particulate flavin-specific fumarate reductase reaction which may involve cytochrome b. Phosphoenolpyruvate (PEP) is carboxylated to oxalacetate by a GDP-specific PEP carboxykinase. Oxalacetate, in turn, is converted to malate by a pyridine nucleotide-dependent malate dehydrogenase. The organism has a NAD-dependent glyceraldehyde-3-phosphate dehydrogenase. The data suggest that reduced pyridine nucleotides generated during glycolysis are oxidized in malate formation and that the electrons generated during pyruvate oxidation are used to reduce fumarate to succinate. 相似文献
998.
Nuclear fractions isolated from Amanita phalloides, Amanita muscaria and Agaricus bisporus were subjected to in vitro RNA synthesis assays in the presence of various concentrations of amatoxins. The mushroom nuclei were highly insensitive to inhibition by amatoxin when compared to assays of nuclear fractions isolated from the Oömycete fungus, Achlya ambisexualis and from rabbit brain.Abbreviations DTT
dithiothreitol
- PMSF
phenylmethyl sulfonyl fluoride
- MES
2[N-morpholino] ethane sulfonic acid
Paper no. 1-78 相似文献
999.
Paul A. Friedman Edward G. Platzer 《Biochimica et Biophysica Acta (BBA)/General Subjects》1978,544(3):605-614
The binding and inhibitory properties of 11 benzimidazoles for bovine brain tubulin were investigated. The effects of the benzimidazoles on the initial rates of microtubule polymerization were determined by a turbidimetric assay. The median inhibitory concentrations (I50) for nocodazole, oxibendazole, parbendazole, mebendazole and fenbendazole ranged from 1.97 · 10−6 to 6.32 · 10−6 M. Benomyl, cambendazole and carbendazim had I50 values from 5.83 · 10−5 to 9.01 · 10−5 M. Thiabendazole had an I50 value of 5.49 · 10−4 M. Inhibitor constants (Ki) were determined by the colchicine binding assay. Oxibendazole, fenbendazole, and cambendazole had Ki values of 3.20 · 10−5, 1.73 · 10−5 and 1.10 · 10−4 M, respectively. Oxibendazole and fenbendazole were competitive inhibitors of colchicine. In contrast, cambendazole was a noncompetitive inhibitor of colchicine. The ability of these benzimidazoles to inhibit microtubule polymerization and the mode of action for the anthelmintic benzimidazoles is discussed. 相似文献
1000.
Peter H. Byers Karen A. Holbrook Judith G. Hall Paul Bornstein John W. Chandler 《Human genetics》1978,40(2):157-169
Summary Several individuals from one family are described with a unique form of spondyloepiphyseal dysplasia. Characteristic features include shorttrunked short stature, punctate corneal dystrophy and marked disorganization of dermal collagen fibrils when examined by transmission electron microscopy. Inheritance is compatible with either dominance and a variable expression or X-linkage. Although the basic defect has not been determined, the tissue distribution is consistent with a defect in a non-collagenous component that affects collagen fibril formation or stability. 相似文献