The proton translocating ATP-synthase from chloroplasts, Cf 0 f 1 , was isolated and reconstituted into asolectin liposomes. [γ- 32 P]ATP hydrolysis was measured under uni-site conditions. When 1 mM unlabeled ATP was...
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The proton translocating ATP-synthase from chloroplasts, Cf 0 f 1 , was isolated and reconstituted into asolectin liposomes. [γ- 32 P]ATP hydrolysis was measured under uni-site conditions. When 1 mM unlabeled ATP was added so that all ATP-binding sites were occupied, [γ- 32 P]ATP bound to the first site, was hydrolyzed with a rate of 0.5 ATP/(Cf 0 f 1 s). In a second experiment, first cold ATP was hydrolyzed under uni-site conditions and then 1 mM [γ- 32 P]ATP was added. This allows under otherwise identical conditions the measurement of the rate of ATP hydrolysis catalyzed by the second (and possibly third) site. It resulted in a rate of 80 ATP/(Cf 0 f 1 s). It is concluded that the catalytic nucleotide binding sites are heterogeneous: there exists one nucleotide binding site which hydrolyzes ATP with a maximal turnover of 0.5/s and another one (or two) which hydrolyze ATP with a turnover of 80/s. The latter one is the catalytic site for maximal turnover.
In the continuing study of antifeedant compounds in Protium javanicum Burm. f. against Coptotermes formosanus Shiraki, 6-desacetylnimbin (1), quercitrin (2) and myricitrin (3) were isolated from P. javanicum extract. ...
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In the continuing study of antifeedant compounds in Protium javanicum Burm. f. against Coptotermes formosanus Shiraki, 6-desacetylnimbin (1), quercitrin (2) and myricitrin (3) were isolated from P. javanicum extract. All compounds were characterised by NMR and MS. furthermore, the structure of 6-desacetylnimbin was confirmed by X-ray crystallography. The antifeedant activity was evaluated with no-choice feeding tests. At a dose of 0.5?mg, 6-desacetylnimbin exhibited the highest antifeedant activity among the isolates.
The leaf alkanes of P. argentatum (guayule), P. tomentosum var. stramonium, P. fruticosum var. trilobatum, and the 1st filial (f1) generations obtained from crosses with guayule were investigated by GC [gas chromatogr...
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The leaf alkanes of P. argentatum (guayule), P. tomentosum var. stramonium, P. fruticosum var. trilobatum, and the 1st filial (f1) generations obtained from crosses with guayule were investigated by GC [gas chromatography] and mass spectrometry[ms] and are useful in chemotaxonomic studies. The identified n-alkanes ranged from C19 to C40 with either n-C29 or n-C31 as the main component. The alkane chemistry of guayule with n-C31 being the main component predominated in most of the f1 hybrids. The presence of iso-branched alkanes (C27, C29, C31) in P. tomentosum and its hybrids could be detected by GC/MS. These preliminary investigations indicate that epiculticular wax alkanes can be useful in inheritance studies of guayule and its hybrids.
Chloroform extract of bark of Artabotrys crassifolius Hook.f. & Thomson exhibited antibacterial activities against both American Type Culture Collection and clinical bacterial strains in vitro with zones of inhibi...
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Chloroform extract of bark of Artabotrys crassifolius Hook.f. & Thomson exhibited antibacterial activities against both American Type Culture Collection and clinical bacterial strains in vitro with zones of inhibition ranging from 7 to 14mm. further analysis of this extract yielded artabotrine, liridine, lysicamine and atherospermidine. Artabotrine displayed a broad array of antibacterial activity mostly against Gram-positive bacteria with minimum inhibitory concentration (MIC) values ranging from 1.25g/mL to 5g/mL. Of note, artabotrine, liridine and lysicamine are bactericidal against Gram-negative extended-spectrum beta-lactamase-producing Klebsiella with MIC values equal 2.5, 2.5 and 10g/mL, respectively, and minimum bactericidal concentrations values equal to 2.5, 5 and 20g/mL.
Cytochrome- f (553–4) was isolated from mass cultures of the six dinoflagellates, Amphidinium carterae (2 strains), Cachonina niei , Glenodinium sp., Peridinium foliaceum , Gonyaulax polyedra , and one chrysophyte, C...
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Cytochrome- f (553–4) was isolated from mass cultures of the six dinoflagellates, Amphidinium carterae (2 strains), Cachonina niei , Glenodinium sp., Peridinium foliaceum , Gonyaulax polyedra , and one chrysophyte, Cricospherae carterae . Sonication of whole cell suspensions released the water-soluble protein, which was then purified by vacuum dialysis, salt fractionation and column chromatography. Reduced forms of isolated cytochromes had absorption maxima at 270–6, 316–8, 415–6, 522–3 and 553–4 rim. The α-absorption peak was asymmetrical. MW's, as determined by SDS polyacrylamide gel electrophoresis, ranged from 10 700 to 13 500. Amino acid analysis of C. niei cytochrome- f revealed 102 residues, with a composite MW of 10836. Purified cytochromes had isoelectric points ranging from 3·45 to 4·25 and oxidation-reduction potentials ranging from +0·374 to +0·351 V.
Under conditions of molar excess of enzyme, isolated f1-ATPase from beef heart mitochondria catalyses ATP hydrolysis biphasically. The rate constants for product release are approximately 10(-1) and 10(-4)-10(-3) s-1,...
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Under conditions of molar excess of enzyme, isolated f1-ATPase from beef heart mitochondria catalyses ATP hydrolysis biphasically. The rate constants for product release are approximately 10(-1) and 10(-4)-10(-3) s-1, respectively. The slow phase of ATP hydrolysis is insensitive to EDTA. [gamma-32P]ATP splitting in the slow phase cannot be chased from the enzyme during several catalytic turnovers. It follows from these results that the slow single-site hydrolysis of ATP (kcat approximately 10(-4) s-1), initially observed by Grubmeyer et al. [(1982) J. Biol. Chem. 257, 12092-12100], is not carried out by the normal catalytic site. In contrast, the phase of rapid ATP hydrolysis (kcat approximately 10(-1) s-1) is completely prevented by EDTA and is believed to be the normal function of the normal catalytic site off1-ATPase.
A rapid, simple and mild process for the dehydration of aldoximes to give the corresponding nitriles, which utilizes SO2f2 as an efficient reagent, has been developed. A variety of (hetero) arene, alkene, alkyne and a...
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A rapid, simple and mild process for the dehydration of aldoximes to give the corresponding nitriles, which utilizes SO2f2 as an efficient reagent, has been developed. A variety of (hetero) arene, alkene, alkyne and aliphatic aldoximes proceeded with high efficiency to afford nitriles in excellent to quantitative yields with great functional group compatibilities in acetonitrile under ambient conditions. furthermore, an eco-friendly synthetic protocol to access nitriles from aldehydes with ortho-, meta-and para-nitrile groups was also described in aqueous methanol by using inorganic base Na2CO3, and a one-pot synthetic strategy to generate nitriles from aldehydes was proved to be feasible.
1. f1-ATPase from eel liver mitochondria at low concentrations preserves unaltered the enzymatic activity for more than 20 min over a temperature range of 6-36-degrees-C. 2. The Arrhenius plot of ATP hydrolysis at sat...
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1. f1-ATPase from eel liver mitochondria at low concentrations preserves unaltered the enzymatic activity for more than 20 min over a temperature range of 6-36-degrees-C. 2. The Arrhenius plot of ATP hydrolysis at saturating substrate concentration appears biphasic with a break-point at 16-degrees-C and activation energies of 14.4 and 56.1 kJ/mol. 3. The ultraviolet, fluorescence and circular dichroism spectra of the enzyme, below and above 16-degrees-C, have been recorded;the fluorescence emission spectra off1-ATPase excited at 275 nm, and the circular dichroism spectra, are different at the two temperatures examined. 4. It is concluded that temperature induces two different conformational states off1-ATPase with different catalytic properties. 5. Ultraviolet spectroscopic features and temperature-dependence of eel liver mitochondrial f1-ATPase are discussed in relation to mammalian f1-ATPases.
Under the conditions of ATP regeneration and molar excess of nucleotide-depleted f1-ATPase the enzyme catalyses steady-state ATP hydrolysis by the single catalytic site. Values of Km = 10(-8) M and Vm = 0.05 s-1 for t...
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Under the conditions of ATP regeneration and molar excess of nucleotide-depleted f1-ATPase the enzyme catalyses steady-state ATP hydrolysis by the single catalytic site. Values of Km = 10(-8) M and Vm = 0.05 s-1 for the single-site catalysis have been determined. ADP release limits single-site ATP hydrolysis under steady-state conditions. The equilibrium constant for ATP hydrolysis at the f1-ATPase catalytic site is less than or equal to 0.7.
Highly purified peroxisomal fractions from rat liver contain ATPase activity (18.8 .+-. 0.1 nmol/min per mg, n = 6). This activity is about 2% of that found in purified mitochondrial fractions. Measurement of marker e...
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Highly purified peroxisomal fractions from rat liver contain ATPase activity (18.8 .+-. 0.1 nmol/min per mg, n = 6). This activity is about 2% of that found in purified mitochondrial fractions. Measurement of marker enzyme activities and immunoblotting of the peroxisomal fraction with an antiserum raised against the .beta.-subunit of mitochondrial ATPase indicates that the ATPase activity in the peroxisomal fractions can not be ascribed to contamination with mitochondria or other subcellular organelles. from the sensitivity of the ATPase present in the peroxisomal fraction towards a variety of ATPase inhibitors, we conclude that it displays both V-type and f-type features and is distinguishable from both the mitochondrial f1f0-ATPase and the lysosomal V-type ATPase.
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