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81.
Baudin Bruno; Alves Nathalie; Pilon Antoine; Beneteau-Burnat Benedicte; Giboudeau Jacqueline 《Glycobiology》1997,7(4):565-570
We enzymatically deglycosylated pig lung angiotensin I-convertingenzyme (ACE) to study the involvement of its glycanic chainsin its physicochemical and catalytic properties. The effectsof endoglycosidases F2 and H, and of N-glycanase were assessedby ACE mobility in SDS-PAGE. N-Glycanase only was completelyeffective with or without previous denaturation, leading toa shift in ACE Mr from 172 to 135 kDa; endoglycosidase F2 producedthe same shift but only without previous denaturation. DeglycosylatedACE had the same kcat as native ACE for the substrate hippuryl-histidyl-leucine,and an identical Stokes radius as measured by size-exclusionhigh performance liquid chromatography. Neuraminidase had noeffect on ACE Stokes radius but slightly decreased its kcatwhich could be related to variations in ionization of the activesite. The isoelectric point of ACE, as, determined by isoelectricfocusing, increased from 4.54.8 to 5.05.3 aftereither endoglycosidase F2 or neuraminidase digestion, but stillwith microheterogeneities which thus did not seem to be relatedto ACE glycans. Deglycosylated ACE did not bind onto agaroselectinsin contrast to native ACE which bound strongly to concanavalinA showing interactions involving oligomannosidic or biantennaryand sialylated N-acetyl-lactosaminic isoglycans. Finally, tunicamycin,an inhibitor of N-glycosylation, did not modify ACE secretionby endothelial cells. Thus, ACE glycans have no drastic effectson structural and biological properties of the protein, butthey may have a functional role on intracellular targeting ofboth secreted and membrane-bound ACE isoforms, also for theprotection of the soluble plasma form against hepatic lectinsand the maintenance of its hydrosolubility. converting enzyme (peptidyldipeptidase EC.3.4.15.1) endothelium glycosidases lectins 相似文献
82.
Nathalie Griffon Catherine Pilon François Sautel Jean-Charles Schwartz Pierre Sokoloff 《Journal of neurochemistry》1997,68(1):1-9
Abstract: As cerebral neurons express the dopamine D1 receptor positively coupled with adenylyl cyclase, together with the D3 receptor, we have investigated in a heterologous cell expression system the relationships of cyclic AMP with D3 receptor signaling pathways. In NG108-15 cells transfected with the human D3 receptor cDNA, dopamine, quinpirole, and other dopamine receptor agonists inhibited cyclic AMP accumulation induced by forskolin. Quinpirole also increased mitogenesis, assessed by measuring [3 H]thymidine incorporation. This effect was blocked partially by genistein, a tyrosine kinase inhibitor. Forskolin enhanced by 50–75% the quinpirole-induced [3 H]thymidine incorporation. This effect was maximal with 100 n M forskolin, occurred after 6–16 h, was reproduced by cyclic AMP-permeable analogues, and was blocked by a protein kinase A inhibitor. Forskolin increased D3 receptor expression up to 135%, but only after 16 h and at concentrations of >1 µ M . Thus, in this cell line, the D3 receptor uses two distinct signaling pathways: it efficiently inhibits adenylyl cyclase and induces mitogenesis, an effect possibly involving tyrosine phosphorylation. Activation of the cyclic AMP cascade potentiates the D3 receptor-mediated mitogenic response, through phosphorylation by a cyclic AMP-dependent kinase of a yet unidentified component. Hence, transduction of the D3 receptor can involve both opposite and synergistic interactions with cyclic AMP. 相似文献
83.
Nathalie Doerflinger Catherine Linder Karim Ouahchi Gabor Gyapay Jean Weissenbach Denis Le Paslier Philippe Rigault Samir Belal Christiane Ben Hamida Faycal Hentati Mongi Ben Hamida Massimo Pandolfo Stephano DiDonato Ronald Sokol Herbert Kayden Pierre Landrieu Alexandra Durr Alexis Brice Fran?oise Goutières Alfried Kohlschütter Pascal Sabouraud Ali Benomar Mohamed Yahyaoui Jean-Louis Mandel Michel Koenig 《American journal of human genetics》1995,56(5):1116-1124
Ataxia with vitamin E deficiency (AVED) is an autosomal recessive disease characterized clinically by neurological symptoms with often striking resemblance to those of Friedreich ataxia. This disorder has been reported previously as familial isolated vitamin E deficiency. We have mapped recently the AVED locus to a 5-cM confidence interval on chromosome 8q by homozygosity mapping in six Mediterranean families. We have now analyzed six new and two previously described families and demonstrate genetic homogeneity despite important clinical variability and wide geographic origins. Analysis of nine new tightly linked microsatellite markers, including four characterized in this study, revealed a predominant but not unique mutation in northern African populations, where this condition is more frequent. Haplotype analysis but also classical recombinations allowed us to refine the AVED position to a 1-cM interval. A YAC contig over this interval was constructed from marker STSs and YAC fingerprint data, in order to facilitate the search of the AVED gene. 相似文献
84.
Proteolytic activity of proteasome on myofibrillar structures 总被引:5,自引:0,他引:5
Richard G. Taylor Caroline Tassy Mariele Briand Nathalie Robert Yves Briand Ahmed Ouali 《Molecular biology reports》1995,21(1):71-73
The physiologic function of proteasome remains unclear. Evidence suggests a role in degradation of ubiquitin-protein conjugates, MHC antigen presentation, and some specificity of substrate within certain cell types. To explore further the properties of proteasome we have examined its effect on a well defined structure, the myofibril. We find that despite its large size (20S) proteasome is able to degrade myofibrils and intact, permeabilized muscle fibrils. The proteins degraded showed some specificity because actin, myosin and desmin were degraded faster than -actinin, troponin T and tropomyosin. Changes in ultrastructure were slow and included a general loss of structure with Z and I bands effected before the M band and costameres. 相似文献
85.
Ulrich Flögel Thoralf Niendorf Nathalie Serkowa Annette Brand Joachim Henke Dieter Leibfritz 《Neurochemical research》1995,20(7):793-802
Diffusion-weighted in vivo1H-NMR spectroscopy of F98 glioma cells embedded in basement membrane gel threads showed that the initial cell swelling to about 180% of the original volume induced under hypotonic stress was followed by a regulatory volume decrease to nearly 100% of the control volume in Dulbecco's modified Eagle's medium (DMEM) but only to 130% in Krebs-Henseleit buffer (KHB, containing only glucose as a substrate) after 7 h. The initial cell shrinkage to approx. 70% induced by the hypertonic stress was compensated by a regulatory volume increase which after 7 h reached almost 100% of the control value in KHB and 75% in DMEM.1H-,13C-and31P-NMR spectroscopy of perchloric acid extracts showed that these volume regulatory processes were accompanied by pronounced changes in the content of organic osmolytes. Adaptation of intra- to extracellular osmolarity was preferentially mediated by a decrease in the cytosolic taurine level under hypotonic stress and by an intracellular accumulation of amino acids under hypertonic stress. If these solutes were not available in sufficient quantities (as in KHB), the osmolarity of the cytosol was increasingly modified by biosynthesis of products and intermediates of essential metabolic pathways, such as alanine, glutamate and glycerophosphocholine in addition to ethanolamine. The cellular nucleoside triphosphate level measured by in vivo31P-NMR spectroscopy indicated that the energy state of the cells was more easily sustained under hypotonic than hypertonic conditions.To whom to address reprint requests. 相似文献
86.
A new monoclonal antibody (3D3) generated with human respiratory mucins and directed against Lewis determinants 总被引:1,自引:1,他引:0
Nathalie Emery; Palfa Shirley B.; Place Graham; Oriol Rafael; Hall Roderick L.; Roussel Philippe; Lhermitte Michel 《Glycobiology》1995,5(6):563-570
We have prepared a monoclonal antibody (MAb), 3D3, raised againstpurified human respiratory mucins. This antibody recognizedmucins and proteolytically derived glycopeptides. The epitoperecognized by the antibody was destroyed by -L-fucosidase, indicatingthat it was present on the carbohydrate moieties. Structuralspecificity was determined by adsorption on a variety of synthetic,insolubilized oligosaccharides. Several lines of evidence indicatethat the 3D3 MAb reacted strongly with the Lewis (Leb) antigen,but also recognized Lea and Ley determinants. This antibodymight be useful to study mucin secretion. human bronchial mucins Lewis b 相似文献
87.
The kinetic mechanism of ox liver glutamate dehydrogenase in the presence of the allosteric effector ADP. The oxidative deamination of L-glutamate. 下载免费PDF全文
In steady-state kinetic studies of ox liver glutamate dehydrogenase in 0.11 M-potassium phosphate buffer, pH7, at 25 degrees C, the concentration of ADP was varied from 0.5 to 1000 microM. Inhibition was observed except when the concentrations of both glutamate and coenzyme were high, when activation was seen. With NAD+ or NADP+ as coenzyme, 200 microM-ADP was sufficient to saturate the enzyme with respect to the major effect of this nucleotide. In the presence of 210 microM-ADP, widely varied concentrations of coenzyme give linear Lineweaver-Burk plots, in marked contrast with results obtained previously for kinetics without ADP. This has allowed evaluation for the reaction with NAD+, NADP+ and acetylpyridine-adenine dinucleotide (315 microM-ADP in the last case) of all four initial rate parameters, i.e. the phi coefficients in the equation: (Formula: see text) where A is coenzyme and B is glutamate. The relative constancy of phi B and of phi AB/phi A with the different coenzymes point to a compulsory-order mechanism with glutamate as the leading substrate. This conclusion, though unexpected, agrees well with various previous observations on the binding of oxidized coenzyme. 相似文献
88.
U. Müller Maria Teresa Zenzes T. Bauknecht U. Wolf J. W. Siebers W. Engel 《Human genetics》1978,45(2):203-207
Summary In a previous report (Zenzes et al., 1978 b) it was shown that dissociated ovarian cells of newborn rats in vitro, if exposed to H-Y antigen, reorganize into testicular structures. The current study was designed to see whether this morphological conversion also results in a functional conversion. The LH/hCG receptor was used as a parameter characteristic for the newborn testis, but not for the newborn ovary. In the converted ovary, the LH/hCG receptor becomes detectable a few hours after onset of the culture and remains continuously present afterward. The appearance of this receptor may be due to a hormone-like action of H-Y antigen. 相似文献
89.
Shen K. Yang Harry V. Gelboin John D. Weber V. Sankaran Daniel L. Fischer James F. Engel 《Analytical biochemistry》1977
The optical isomers of (±)r-7,t-8-dihydroxy-7,8-dihydrobenzo[a]pyrene and its synthetic precursor (±)r-7,t-8-dihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene were resolved as their di-(−)menthoxyacetates using high-pressure liquid chromatography. Saponification of the resolved diesters yielded the corresponding enantiomers. The specific rotation, CD spectra, and ORD curves are reported. The resolution of these optical isomers permits detailed studies on the enzymatic intermediates and the mechanism of benzo[a]pyrene activation to its carcinogenic form. The method is of general usefulness for the resolution of optical isomers. 相似文献
90.