Showing papers by "University of Nice Sophia Antipolis published in 1977"
TL;DR: The induction of these two proteins by glucose starvation suggests that they have a role in glucose utilization, and two glucose derivatives, glucosamine and 2-deoxyglucose, are known to interfere with the glycosylation process.
274 citations
185 citations
TL;DR: In this paper, it was shown that π − π− correlations due to the analogue of the Hanbury Brown-Twiss effect are narrower than those currently observed, the latter being due to more complicated interferences.
67 citations
56 citations
TL;DR: In this article, the authors look for the Besov spaces to which the product f × g belongs so that the multiplication is a continuous mapping, and then they find the corresponding Sobolev spaces.
Abstract: Let f, g be two functions of two Besov spaces (or Sobolev spaces), we look for the Besov spaces to which the product f × g belongs so that the multiplication is a continuous mapping.
43 citations
TL;DR: Milk alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.1) is an enzyme which requires two types of metals for maximal activity: zinc and magnesium, which is essential and stimulatory, respectively.
41 citations
TL;DR: Freezing and thawing of cells before homogenization allow a final purification of at least 10-fold with a 6% yield, based upon the determination of ouabain-sensitive K + -dependent p -nitrophenylphosphatase and of insulin binding.
38 citations
TL;DR: The present results give support to interprotomer catalytic cooperativity in the mechanism of action of yeast phenylalanyl-tRNA synthetase.
Abstract: Yeast phenylalanyl-tRNA synthetase, an enzyme with an α2β2 structure, has two active sites for phenylalanine, tRNAPhe, phenylalanyladenylate and phenylalanyl-tRNAPhe. Determination of phenylalanine binding properties to the free enzyme by equilibrium dialysis shows that only one mole of amino acid binds per mole of enzyme, i.e. absolute negative cooperativity. Binding of the amino acid in the presence of tRNA or of ATP and PPi unmasks the second phenylalanine binding site. The difference between the affinities at the tight and loose binding sites under such conditions is about 10–15. Titration of phenylalanyladenylate sites by the burst of ATP consumption shows the formation of a (enzyme-phenylalanyladenylate)2 complex in the presence of pyrophosphatase; however, the two sites differ widely in their affinity as shown by dialysis experiments. Measurements of hydrolysis rates of enzyme-bound phenylalanyladenylate suggests that when only the high-affinity adenylate site is occupied, the other protomer can still bind phenylalanine and ATP (in the presence of phenylalanine). Two moles of Phe-tRNAPhe bind to the enzyme with a very high affinity (Kd < 48 nM). The presence of millimolar concentrations of ATP, phenylalanine and pyrophosphate triggers negative cooperativity and under these conditions only one mole of Phe-tRNAPhe is bound per mole of enzyme with a Kd value of 0.15 μM. The present results give support to interprotomer catalytic cooperativity in the mechanism of action of yeast phenylalanyl-tRNA synthetase.
37 citations
33 citations
TL;DR: Observable labile protons with deuterium of the solvent were markedly different, showing that the molecular structure of the cardiotoxin must be more flexible than that of the neurotoxin and suggesting that the different functional properties of the two toxins might be related to the different molecular dynamics.
31 citations
TL;DR: In this paper, the authors studied the asymptotic decay of functions u ∊ L 2 (Ω) which are solutions of the following problem: Δ u + cu = 0.
Abstract: In an unbounded domain Ω we study the asymptotic decay (for | x |→∞) of functions u ∊ L 2 (Ω) which are solutions of the following problem –Δ u + cu = 0. c denotes a strictly positive function. Upper bounds are easily found via the maximum principle. When c is rotationally invariant lower bounds are obtained via asymptotic expansion. In the general case we use a method of ‘commutation’ of operators. In particular we consider the case where . Applications to the asymptotic decay of the bound states of a Hamiltonian are given.
TL;DR: For the three liquid methylhalides, CHF3, CH3F, and CH3Cl, a correlation function analysis of the rotational motion, extended over all the liquid-gas coexistent states, is presented in this article.
Abstract: For the three liquid methylhalides, CHF3, CH3F, and CH3Cl, we describe a correlation function analysis of the rotational motion, extended over all the liquid-gas coexistent states. These orientational correlation functions are exponential at long times and damped oscillatory at short times. Experimental memory functions are computed, and a comparison with the rotational velocity correlation functions show generally acceptable agreement. The nature of the microscopic motion in the frame of either Cole-Glarum or Fatuzzo-Mason theories is compared, indicating generally weak deviations. Some examples are presented of the amplitudes of mean squared torques and their variations under orthobaric conditions. The physical situation in fluoroform is further analysed with the help of τ1/τ2 ratios, indicating that in this liquid a satisfactory description is gained with the itinerant oscillator model. Finally, the validity of the collisional models under their various formulations is shown to be, at the least, dubious.
TL;DR: A detailed comparison is carried out between the theoretical results and experimental data on the crystal structure of tRNAPhe produced by four different groups of investigators.
TL;DR: Comparison of experimental data shows an equal contribution of upper and lower layers to the limitation of the optical seeing in the integrated refractive-turbulence profiles of two regions of the atmosphere.
Abstract: We measure the wavefront coherence and the irradiance fluctuations of stellar sources to obtain integrated refractive-turbulence profiles of two regions of the atmosphere. Comparison of experimental data during our measurement program shows an equal contribution of upper and lower layers to the limitation of the optical seeing. We also note the great variability of turbulence located above 3 km up to the stratosphere, from night to night. When simultaneously operated, these two methods are suitable for astronomical site testing.
TL;DR: In this article, the longitudinal and transverse correlation functions for the fluctuations in the angle of arrival on the entrance pupil of a solar telescope have been estimated and the results are found to be consistent with the inertial model of turbulence.
Abstract: The longitudinal and transverse correlation functions for the fluctuations in the angle of arrival on the entrance pupil of a solar telescope have been estimated. The results are found to be consistent with the inertial model of turbulence. Values of the integral ∫CN2dh of the structure constant over the lower atmospheric layers and of Fried’s seeing parameter r0 are deduced. They are found to be consistent with other independent estimations made with the same telescope.
TL;DR: It is concluded that after esterification of tRNA, the aminoacyl residue still binds the enzyme, probably within the methionine activating site, and the latter behaviour may account for the observation that excess Methionine accelerates the aminoACYlation turnover rate of t RNA(Met/f).
Abstract: Binding of tRNA(Met/f) to the monomeric trypsin-modified methionyl-tRNA synthetase turns off the methionine-dependent isotopic ATP--PPi exchange. In the case of the dimeric native methionyltRNA synthetase, one anticooperatively bound tRNA(Met/f) inhibits the exchange by only 50%. These behaviours of tRNA do not require the integrity of the 3'-terminal adenosine. Esterification by methionine of the 3' end of tRNA reinforces the affinity of tRNA(Met/f)for the enzymes. In the case of the native enzyme, due to this effect, a second binding mode for methionyl-tRNA may be demonstrated through the isotopic exchange. This additional binding of tRNA corresponds to the expression of the anticooperatively blocked tRNA binding site. Methionine reverses competitively the reinforcing effect of the esterified methionyl moiety on tRNA binding. It is concluded that after esterification of tRNA, the aminoacyl residue still binds the enzyme, probably within the methionine activating site. The latter behaviour may account for the observation that excess methionine accelerates the aminoacylation turnover rate of tRNA(Met/f).
01 Jan 1977
TL;DR: Certain domain identification problems can be formulated in the following way : minimize the functional J(Ω) , Ω belonging to a given family of domains.
Abstract: Certain domain identification problems can be formulated in the following way : minimize the functional J(Ω) , Ω belonging to a given family of domains.
TL;DR: In this paper, a new technique called "one-dimensional speckle-interferometry" was proposed for high-resolution astronomical measurements, which appeared to be a good compromise between standard specckle interferometers and Michelson interferometry.
TL;DR: In this paper, the transmission coefficient de transmission, portee des electrons dans lames minces d'aluminium and les distributions of electrons transmisis were investigated. Butteau et al. concerne la transmission d'electrons d'energie comprise entre 0,7 and 3 keV.
TL;DR: In this article, the parton picture of regge theory is extended to the supercritical case α p > 1, and the essential results of Amati et al. and others are rederived by heuristic but mathematically very simple arguments.
TL;DR: In this paper, the average hydrodynamic radius of synthetic phospholipid vesicles and the variance of the size distribution were measured by dynamic light scattering spectroscopy near the lipid phase transition.
TL;DR: The Association des Ostracodes appartient a la meme province ecologique que celle du Bassin de Paris mais se differencie de celle qui caracterise le domaine subalpin this article.
TL;DR: In this article, the authors examined 19F chemical shifts for ca. 650 F-alkylated compounds of general formula CF3(CF2)nCF2X and found that the CF2 groups α to X are very sensitive to the nature of X, and are spread over a range of 85 ppm.
TL;DR: Among the numerous steroids tested for cross reactivity androstenedione and 5α-DHT showed 19% and 3.2%Cross reactivity respectively at the 50% level and 1 ng were made.
TL;DR: In this article, the carbon-13 shifts of C-1, C-2 and C-3 are determined in a series of 1-cyclohexen-3-ones substituted in position 1, showing a relative independence of the substituent effect for this nucleus from the variation of the unsaturated framework.
Abstract: The carbon-13 shifts of C-1, C-2 and C-3 are determined in a series of 1-cyclohexen-3-ones substituted in position 1. Linear relationships are demonstrated between the substituent chemical shifts of corresponding carbons in substituted ethylenes, butadienes, α-enones and benzenes. The substituent chemical shifts of proton H-2 are also reported and correlated with those of corresponding protons in ethylenes and benzenes. The slopes of the lines for the carbons directly linked to the substituent are close to unity, showing a relative independence of the substituent effect for this nucleus from the variation of the unsaturated framework. In contrast to this, the transmission of the substituent effect through one double bond (nuclei β to the substituents) decreases as the number of conjugated π bonds in the whole structure increases. This relationship is interpreted as being due to the ability of an unsaturated system to spread the variation of π electron density induced by the substituent.
TL;DR: In this article, a simple method based on Sephadex gel column chromatography and requiring only small quantities of plant material, enabled not only the separation of betacyanins from betaxanthins but also the isolation of several different species of each of these types of pigment.
01 Jan 1977
TL;DR: The stability of such associations is due to a variety of intermolecular forces, such as van der Waals-London forces or hydrogen bonding, which are weaker and less well understood than the forces involved in a simple chemical reaction.
Abstract: Molecular associations between two or more components not involving true chemical bonding have been studied extensively.1,2 They play a crucial role in some of the more recent developments in modern biology. The stability of such associations is due to a variety of intermolecular forces, such as van der Waals-London forces or hydrogen bonding, which are weaker, and less well understood, than the forces involved in a simple chemical reaction.
TL;DR: Sclerasterias richardi, a seastar living on the border (120 to 200 m) of the Mediterranean Continental Shelf, displays fissiparity concomitant with sexual reproduction.
Abstract: Sclerasterias richardi, a seastar living on the border (120 to 200 m) of the Mediterranean Continental Shelf, displays fissiparity concomitant with sexual reproduction. In order to describe the as yet unknown larva, artificial fecundation was induced in specimens collected in October, 1975. To obtain gametes, the seastars were treated with a 3x10-6 M 1-methyladenine solution injected into the coelomic cavity. Histological study of the gonads revealed that the low proportion of the treated sample responding positively was due to the experiments being conducted at the end of the natural spawning period. The behaviour of males during sperm emission is described and discussed. Our observations suggest that S. richardi would exhibit “epidemic sexuality” under natural conditions. The development of fertilized ova, observed over a period of 42 days, produces planktotrophic larvae, the first photographs of which are presented.
TL;DR: In chromatographic studies polar effect constants σ*c, similar to those of Taft and Ingold, can be obtained from an empirical additivity relationship which takes into account three structural increments as mentioned in this paper.