Site-directed mutagenesis of glutamate 166 in two beta-lactamases. Kinetic and molecular modeling studies.
; ; et al
in Journal of Biological Chemistry (1997), 272(9), 5438-44
The catalytic pathway of class A beta-lactamases involves an acyl-enzyme intermediate where the substrate is ester-linked to the Ser-70 residue. Glu-166 and Lys-73 have been proposed as candidates for the ... [more ▼]
The catalytic pathway of class A beta-lactamases involves an acyl-enzyme intermediate where the substrate is ester-linked to the Ser-70 residue. Glu-166 and Lys-73 have been proposed as candidates for the role of general base in the activation of the serine OH group. The replacement of Glu-166 by an asparagine in the TEM-1 and by a histidine in the Streptomyces albus G beta-lactamases yielded enzymes forming stable acyl-enzymes with beta-lactam antibiotics. Although acylation of the modified proteins by benzylpenicillin remained relatively fast, it was significantly impaired when compared to that observed with the wild-type enzyme. Moreover, the E166N substitution resulted in a spectacular modification of the substrate profile much larger than that described for other mutations of Omega-loop residues. Molecular modeling studies indicate that the displacement of the catalytic water molecule can be related to this observation. These results confirm the crucial roles of Glu-166 and of the "catalytic" water molecule in both the acylation and the deacylation processes. [less ▲]Detailed reference viewed: 7 (0 ULg)
Etude d'un projet de centre commercial. Projet Résidentia, Parc de l'Alliance, Braine-l'Alleud
Halleux, Jean-Marie ; ; Merenne-Schoumaker, Bernadette
Report (1997)Detailed reference viewed: 27 (1 ULg)
Production de molécules à note verte par synthèse enzymatique.
; ; Fauconnier, Marie-Laure
Report (1997)Detailed reference viewed: 13 (0 ULg)
Pregnancy-Associated Glycoprotein (PAG) profiles during pregnancy and postpartum and progesterone (P4) profiles during pregnancy in native goats from Northeast of Brazil.
Melo de Sousa, Noelita ; ; et al
in Arquivos - Faculdade de Veterinária, UFRGS (1997), 25(1 (Suppl)), 304-305Detailed reference viewed: 6 (1 ULg)
La problématique du réseau écologique : Bases théoriques et perspectives d’une stratégie écologique d’occupation et de gestion de l’espace
in Colloque international Le Réseau écologique (1997)Detailed reference viewed: 72 (21 ULg)
Plasma bovine pregnancy-associated glycoprotein concentrations throughout gestation in relationship fetal number in the cow
; Sulon, Joseph ; Beckers, Jean-François et al
in European Journal of Endocrinology (1997), 137
This study characterized the peripheral plasma bovine pregnancy-associated glycoprotein (bPAG) profile throughout gestation and examined the effect of stage of gestation and fetal number on this profile ... [more ▼]
This study characterized the peripheral plasma bovine pregnancy-associated glycoprotein (bPAG) profile throughout gestation and examined the effect of stage of gestation and fetal number on this profile in Holstein cows after non-surgical embryo transfer. Cows (n = 12) were divided into three groups: group 1 = normal singleton pregnancies (n = 5); group 2 = normal twin pregnancies (n = 5); group 3 = abnormal twin pregnancies (n = 2). Blood was collected about every third day from day 0 (defined as the first day of standing estrus), then daily for the last 10 days of gestation, and sampling was stopped one day postpartum. The time-related changes in plasma bPAG concentrations were significantly (P < 0.01) affected by the stage of gestation and fetal number (P < 0.01), except during the last 10 days of gestation. In both normal pregnancy groups, bPAG concentration increased rapidly during the first trimester (0.5 +/- 0.1 to 14.6 +/- 1.7 ng/ml and 1.0 +/- 0.6 to 21.8 +/- 4.8 ng/ml, in singleton and twin-bearing groups respectively), then progressively between days 160 and 20 prepartum (31.6 +/- 6.2 to 114.3 +/- 31.3 ng/ml and 41.6 +/- 7.4 to 155.8 +/- 36.6 ng/ml in singleton and twin-bearing cows respectively). The mean concentration between days 20 and 10 prepartum approximately tripled (P < 0.001) in both these groups of cows (114.3 +/- 31.1 to 493.0 +/- 75.3 ng/ml and 155.8 +/- 36.6 to 409.3 +/- 114.7 ng/ml in singleton and twin-bearing cows respectively), but between days 10 prepartum and parturition the values increased about threefold (P < 0.01) in the singleton group (493.0 +/- 75.3 to 1352.8 +/- 286.5 ng/ml) and fivefold (P < 0.001) in the twin-bearing group (409.3 +/- 114.7 to 2154.0 +/- 505.7 ng/ml). The two cows in group 3 that gave birth prematurely to a stillborn calf or to a schistosomus reflexus calf exhibited an aberrant bPAG profile. Our results indicate that peripheral bPAG concentrations are correlated to the stage of gestation and fetal number, and that the profile of the peripheral plasma concentrations provides a useful indication of the feto-placental status. [less ▲]Detailed reference viewed: 29 (3 ULg)
Rayonnement différentiel, spécialisation et vitalité commerciale : réflexions sur les pôles périphériques traditionnels des agglomérations belges à partir de lʼexemple de Jemeppe-sur-Meuse
in Revue Belge de Géographie (1997), (1-2-3-4), 139-148Detailed reference viewed: 30 (6 ULg)
New Primers For The Polymerase Chain Amplification Of Cpdna Intergenic Spacers In Phaseolus Phylogeny
; ; Baudoin, Jean-Pierre et al
in Belgian Journal of Botany (1997), 129(2),Detailed reference viewed: 5 (0 ULg)
Inception of Taeniate Bisaccates pollen: further evidence and age implications for the Monte Alegre Formation (Pennsylvanian, Amazon Basin).
; ; et al
in Annals Academia Brazil Cienca (1997)Detailed reference viewed: 17 (0 ULg)
The dynamics of the karstic features of Sprimont (Belgium) and its consequences on the land-use planning. Preliminary note.
Ek, Camille ; ; et al
in Proceedings of tne 12th International Congress of Speleology (1997)
The Department of Physical Geography of the University of Liège (Belgium) was in charge of updating the physical factors of the regional land management map for Sprimont, a karstic municipality of Belgium ... [more ▼]
The Department of Physical Geography of the University of Liège (Belgium) was in charge of updating the physical factors of the regional land management map for Sprimont, a karstic municipality of Belgium. The influence of floods, karst processes, landslides, and other physical factors were evaluated. The karst features and karst-related events have been mapped three times with accuracy in this area during the last century (in 1898, 1971 and 1996). The data provided the basis for a study of the rates and dynamics of the karst processes and permitted the forecasting of hazards on a secular basis. A map of karstic areas, karst features and karst dynamics was prepared. Some systematic trends of the evolution of karst features were noted. A map of risks and land-use constraints was derived from the first map and from the observed trends. Rules were induced from these data and were proposed to control building and other activities in clearly defined areas. [less ▲]Detailed reference viewed: 18 (4 ULg)
29. Lessons learned from the thermal design of an instrument (EIT, the Extreme-UV Imaging Telescope) on board SOHO
in IAF (1997)Detailed reference viewed: 34 (5 ULg)
In-orbit diagnostics of EIT EUV CCD radiation-induced aging
Defise, Jean-Marc ; ; et al
in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1997)Detailed reference viewed: 15 (1 ULg)
First Results from EIT
; ; et al
in 1st Advances in Solar Physics Euroconference. Advances in Physics of Sunspots (1997)
The Extreme-UV Imaging telescope has already produced more than 15000 wide-field images of the corona and transition region, on the disk and up to 1.5R_o above the limb, with a pixel size of 2.6\arcsec ... [more ▼]
The Extreme-UV Imaging telescope has already produced more than 15000 wide-field images of the corona and transition region, on the disk and up to 1.5R_o above the limb, with a pixel size of 2.6\arcsec. By using four different emission lines, it provides the global temperature distribution in the quiet corona, in the range 0.5 to 3*E(6) K. Its excellent sensitivity and wide dynamic range allow unprecedented views of low emission features, even inside coronal holes. Those so-called ``quiet'' regions actually display a wide range of dynamical phenomena, in particular at small spatial scales and at time scales going down to only a few seconds, as revealed by all EIT time sequences of full- or partial-field images. The initial results presented here demonstrate the importance of this wide-field imaging experiment for a good coordination between SOHO and ground-based solar telescopes, as well as for science planning. [less ▲]Detailed reference viewed: 19 (4 ULg)
Autoregulation of endogenous glucose production in man.
; ; Paquot, Nicolas
in Biochemical Society Transactions (1997), 25(1), 11-3Detailed reference viewed: 5 (1 ULg)
Pemphigus foliacé dans l'espèce équine : synthèse et description de 2 cas.
Amory, Hélène ; ; Desmecht, Daniel et al
in Annales de Médecine Vétérinaire (1997), 141Detailed reference viewed: 93 (19 ULg)
Long-wavelength behavior of the exchange-correlation kernel in the Kohn-Sham theory of periodic systems
Ghosez, Philippe ; ;
in Physical Review. B : Condensed Matter (1997), 56(20), 12811-12817
The polarization dependence of the exchange-correlation (re) energy functional of periodic insulators within Kohn-Sham (KS) density-functional theory requires a O(1/q(2)) divergence in the re kernel for ... [more ▼]
The polarization dependence of the exchange-correlation (re) energy functional of periodic insulators within Kohn-Sham (KS) density-functional theory requires a O(1/q(2)) divergence in the re kernel for small vectors q. This behavior, exemplified for a one-dimensional model semiconductor, is also observed when an insulator happens to be described asa KS metal, or vice versa. Although it can occur in the exchange-only kernel, it is not found in the usual local, semilocal, or even nonlocal approximations to KS theory. We also show that the test-charge and. electronic definitions of the macroscopic dielectric constant differ from one another in exact KS theory, but are equivalent in the above-mentioned approximations. [less ▲]Detailed reference viewed: 7 (0 ULg)
Un prince en faillite. Jean de Flandre, évêque de Metz (1279/80-1282), puis de Liège (1282-1291)
Book published by Académie royale de Belgique - Commission royale d'Histoire (1997)Detailed reference viewed: 25 (6 ULg)