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81.
A solubilized preparation of the major Rhodospirillum rubrum antenna complex (B880) was obtained by a described procedure and its polypeptide composition was analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Only two polypeptides of molecular weights close to 7000 were detected after staining the gels with Coomassie brilliant blue. However, several other constituents could be visualized by silver staining or by an immunochemical method. When the preparation was chromatographed on Sephacryl, some of the resulting fractions exhibited the characteristic B880 absorption spectrum and contained only the two proteins that were detectable with Coomassie brilliant blue. In those fractions the A
280/A
880ratio was 0.4, which indicated a significant improvement of the bacteriochlorophyll to protein ratio over the unchromatographed preparation (A
280/A
880=0.7). Other chromatography fractions lacked bacteriochlorophyll and contained a carotenoid which seemed to be bound to protein. The macromolecular constituents present in these latter fractions differed from those associated to the purified B880 complex in their electrophoretic moblities and/or in their staining properties. That suggested the possible existence of a carotenoprotein that did not result from the B880 complex upon loss of bacteriochlorophyll. 相似文献
82.
Effect of prolactin and glucocorticoids on P-enolpyruvate carboxykinase activity in liver and mammary gland from diabetic and lactating rats 总被引:1,自引:0,他引:1
María F. Lobato Mertxe Careche Manuel Ros Francisco J. Moreno Josefa P. García-Ruíz 《Molecular and cellular biochemistry》1985,67(1):19-23
Summary The administration of 2 bromo--ergocryptine, to reduce serum prolactin decreased the activity of cytosolic P-enolpyruvatc carboxykinase (GTP) (EC4.1.1.32) about 50% in both liver and mammary gland of lactating animals. Adrenalectomy had similar effects to those of bromo-a-ergocryptine. In contrast, there was a 50% increase in enzyme activity in the mammary gland of diabetic, lactating rats and a 10-fold increase in liver as compared with normal rats. P-enolpyruvate carboxykinase activity in mammary gland as liver is coordinately regulated by prolactin, glucocorticoids and insulin. 相似文献
83.
Javier G. Fernández Velasco Norma L. Pucheu Oscar Romero Norma L. Kerber Raúl A. Fernández Augusto F. García 《Archives of microbiology》1985,143(2):192-195
The conditions under which an oscillatory behaviour is observed during net hydrolysis or synthesis of ATP in chromatophores of Rhodospirillum rubrum FR1 are described. In the case of ATPase the oscillations are observed at low temperature (ca. 11°C) in the dark after an initial transient behaviour. These oscillations are attenuated or disappear by the addition of an uncoupler.Oscillations are also observed during ATP synthesis. At 3°C the oscillations appear spontaneously if photophosphorylation is measured during a sufficiently long time. At 30°C the mere intercalation of a dark period also at 30°C is sufficient to trigger the oscillations in the following light period.Abbreviations Bchl
Bacteriochlorophyll
- FCCP
carbonyl cyanide p-trifluoromethoxyphenyl hydrazone
- PMS
phenazine methosulfate
- TMPD, N,N,N,N
tetramethyl-1,4-phenylenediamine
Dedicated to Prof. Dr. Gerhart Drews as a homage for his permanent example as hard worker and careful scientist and also for his remarkable human quality 相似文献
84.
Differential effect of pertussis toxin on the affinity state for agonists of renal alpha 1- and alpha 2- adrenoceptors 总被引:4,自引:0,他引:4
J L Boyer A García C Posadas J A García-Sáinz 《The Journal of biological chemistry》1984,259(13):8076-8079
The effect of pertussis toxin treatment on the guanine nucleotide-induced modulation of the affinity of renal alpha 1- and alpha 2-adrenergic receptors was investigated. Pretreatment of rats with pertussis toxin did not induce any change in the number of or affinity for antagonists of alpha 1- or alpha 2-receptors studied using [3H]prazosin and [3H]yohimbine, respectively. Guanyl-5'-yl imidodiphosphate induced an "up-shift" in the number of alpha 2-adrenergic receptors; this up-shift was not observed for alpha 1-adrenergic receptors. Pertussis toxin treatment decreased the affinity of epinephrine for the [3H]yohimbine-binding sites and reduced the ability of guanine nucleotides to modulate alpha 2-adrenoceptor agonist affinity. The regulation by guanine nucleotides of alpha 1-adrenoceptor affinity for agonists was not altered. These results suggest that the modulation of alpha 1- and alpha 2-adrenoceptors by guanine nucleotides is probably exerted through different molecular entities. 相似文献
85.
Luis M. Vázquez de Miguel José A. Serrano Blázquez Fernando J. García Barros Manuel Gómez Guillén 《Carbohydrate research》1984,126(1):81-90
Ethyl 2-amino-4,6-O-benzylidene-2-deoxy-d-gluconate adds to acetylenic esters to give sugar enaminones. The following acetylene derivatives have been employed: methyl propiolate, ethyl phenylpropiolate, and dimethyl acetylenedicarboxylate (6). With compound 6, the reaction leads to a mixture of the expected enaminone and the isomeric oxazolidine derivative. The structures and configurations of the new compounds were studied by spectroscopic and chemical methods. 相似文献
86.
87.
The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel. 相似文献
88.
M C Hidalgo M García G Cardenete A Sanz M de la Higuera 《Revista Espanola de Fisiología》1986,42(2):191-198
After 36% of hepatic mass removal , rainbow trout recovered its initial liver weight in 20-30 days, i.e., with a regeneration rate clearly lower than in mammals. During early regeneration process hematocrit index and hemoglobin content were slightly decreased, but both parameters rapidly reached their normal values. The evolution of both glycaemia and hepatic glycogen content supported the idea of the existence of a late regeneration wave, which, in this case, could begin at about the 20th post-operative day. 相似文献
89.
Study of the hydrolysis and ionization constants of Schiff base from pyridoxal 5''-phosphate and n-hexylamine in partially aqueous solvents. An application to phosphorylase b. 下载免费PDF全文
J Donoso F Mu?oz A García Del Vado G Echevarría F García Blanco 《The Biochemical journal》1986,238(1):137-144
Formation and hydrolysis rate constants as well as equilibrium constants of the Schiff base derived from pyridoxal 5'-phosphate and n-hexylamine were determined between pH 3.5 and 7.5 in ethanol/water mixtures (3:17, v/v, and 49:1, v/v). The results indicate that solvent polarity scarcely alters the values of these constants but that they are dependent on the pH. Spectrophotometric titration of this Schiff base was also carried out. We found that a pKa value of 6.1, attributed in high-polarity media to protonation of the pyridine nitrogen atom, is independent of solvent polarity, whereas the pKa of the monoprotonated form of the imine falls from 12.5 in ethanol/water (3:17) to 11.3 in ethanol/water (49:1). Fitting of the experimental results for the hydrolysis to a theoretical model indicates the existence of a group with a pKa value of 6.1 that is crucial in the variation of kinetic constant of hydrolysis with pH. Studies of the reactivity of the coenzyme (pyridoxal 5'-phosphate) of glycogen phosphorylase b with hydroxylamine show that this reaction only occurs when the pH value of solution is below 6.5 and the hydrolysis of imine bond has started. We propose that the decrease in activity of phosphorylase b when the pH value is less than 6.2 must be caused by the cleavage of enzyme-coenzyme binding and that this may be related with protonation of the pyridine nitrogen atom of pyridoxal 5'-phosphate. 相似文献
90.
Nucleotide sequence and expression of the pneumococcal autolysin gene from its own promoter in Escherichia coli 总被引:32,自引:0,他引:32
Autolysins are enzymes that have several important biological functions and also seem to be responsible for the irreversible effects induced by the beta-lactam antibiotics. The pneumococcal autolysin gene (lyt) has been subcloned from the plasmid pGL30 [García et al., Mol. Gen. Genet. 201 (1985) 225-230] and we have found that the E form of the autolysin is synthesized in Escherichia coli using its own promoter. The high amount of autolysin obtained in the heterologous system when the lyt gene is present in different orientations in the recombinant plasmids studied supports the idea that the autolysin promoter could be a strong one. The nucleotide sequence of the HindIII fragment of pGL80 (1213 bp) containing the autolysin structural gene has been determined. A unique open reading frame (ORF) has been found, a consensus ribosome-binding site and -10 and -35 promoter-like sequences as well as A + T-rich regions farther upstream were also identified. The lyt ORF encodes a protein of 318 amino acid residues having a calculated Mr of 36,532, which agrees with previous size estimates based on electrophoretic migration [H?ltje and Tomasz, J. Biol. Chem. 251 (1976) 4199-4207; Briese and Hakenbeck, Eur. J. Biochem. 146 (1985) 417-427]. Our results also demonstrate that the lyt-4 marker represents the first example of a mutation in a structural gene of a bacterial autolysin. The polarity profile of the pneumococcal autolysin supports previous suggestions about the localization of this enzyme in the normal cell. 相似文献